Ww. G. FARLOW

HARVARD BOTANI

=

At a meeting of the Botanical Department held
Oct. 20, 1903, the following vote was passed:

“Under the head of Harvard Botanical Memoirs it is
proposed to include all quarto publications issuing from
the Gray Herbarium, the Cryptogamic Herbarium, and
the Botanical Laboratories of Harvard University, including
theses presented for the degrees of Ph.D. and S.D. in Botany.
Inasmuch as some of the future publications are likely to be
continuations of subjects treated in quarto papers already
published, it seemed desirable to begin the numbering of the
Memoirs with the year 1880, the date of the first quarto
publication of any member of the botanical staff at present
connected with Harvard University.”

At a meeting on Nov. 25, 1916, it was voted to dis-
continue the series of Botanical Memoirs. In all, nine
numbers have been issued, the titles of which are given
below.

. I. The Gymnosporangia or Cedar-Apples of the United States.
By W. G. Farlow. Anniversary Memoirs, Boston Soc.
Nat. Hist. 1880. Pp. 38. Pls. 1 and 2.

II. The Entomopthoreae of the United States. By Roland
Thaxter. Mem. Boston Soc. Nat. Hist., IV, No. 6. Pp.
133-201. Pls. 14-21. April, 1888.

Il. The Flora of the Kurile Islands. By K. Miyabe. Mem.
Boston Soc. Nat. Hist., 1V, No. 7. Pp. 203-275. Pl. 22.
Feb. 1890.

IV. A North American Anthurus: its Structure and Development.
By Edward A. Burt. Mem. Boston Soc. Nat. Hist., TI,
No. 14. Pp. 487-505. Pls. 49 and 50. Oct. 1894.

V. Contribution towards a Monograph of the Laboulbeniaceae.
By Roland Thaxter. Mem. American Acad. of Arts and
Sci. Boston. XII, No. 3. Pp. 189-429. Pls. 1-26.
Presented May 8, 1895. Issued Oct. 14, 1896.

VI. The Development, Structure, and Affinities of the Genus
Equisetum. By Edward C. Jeffrey. Mem. Boston Soc.
Nat. Hist., V, No. 5. Pp. 155-190. Pls. 26-30. April,
1899.

ee | VIL. : Comparative Anatomy and Phyllogeny of the Coni-
ferales, Part I. The Genus Sequoia. By Edward C.
Jeffrey. Mem. Boston Soc. Nat. Hist., V, No. 10. Pp.
441-459. Pls. 68-71. Nov. 1903. :
VIII. The Comparative Anatomy and Phyllogeny of the Coni-
ferales, Part II. The Abietineae. By Edward C. Jeffrey.
Mem. Boston Soc. Nat. Hist., VI, No. 1. Pp. 1-37. Pls.
1-7. Jan. 1905.
IX. Contributions towards a Monograph of the Laboulbeniaceae,
Part II. By Roland Thaxter. Mem. American Acad. of
Arts and Sct., XIII, No. 6. Pp. 219-469. Pls. 28-71.
June, 1908.

| th
ConltenAs of HG rk rege

75,8559 nOs.1-o

HARVARD BOTANICAL MEMOIRS

Under the head of Harvard Botanical Memoirs it is
proposed to include all quarto publications issuing from
the Gray Herbarium, the Cryptogamic Herbarium, and
the Botanical Laboratories of Harvard University, in-
cluding theses presented for the degrees of Ph.D. and
S.D. ia Botany. Inasmuch as some of the future
publications are likely to be continuations of subjects

treated in quarto papers already published, it seemed

desirable to begin the numbering of the Memoirs with

the year 1880, the date of the first quarto publication
of any member of the botanical staff at present con-

nected with Harvard University.

I. The Gymnosporangia or Cedar-Apples of the United States.
By W. G. Farlow. Anniversary Memoirs, Boston Soc.
Nat. Hist. 1880. Pp. 38. Pls. 1 and 2.

The Entomopthoraceae of the United States. By Roland
Thaxter. Mem. Boston Soc. Nat. Hist., 1V, No.6. Pp.
133-201. Pls. 14-21. April, 1888.

The Flora of the Kurile Islands. By K. Miyabe. Mem.
Boston Soc. Nat. Hist., IV, No.7. Pp. 203-275. Pl. 22.
Feb. 1890.

A North American Anthurus: its Structure and Development.
3y Edward A. Burt. Mem. Boston Soc. Nat. Hist., U1,
No. 14. Pp. 487-505. Pls. 49 and 50. Oct. 1894.

Contributions towards a Monograph of the Laboulbeniaceae.
By Roland Thaxter. Mem. American Acad. of Arts and
Sci. Boston. XII, No. 3. Pp. 189-420. Pls. 1-26.
Presented May 8, 1895. Issued Oct. 14, 1896.

The Development, Structure, and Affinities of the Genus
Equisetum. By Edward C. Jeffrey. Mem. Boston Soc.
Nat. Hist., V, No.5. Pp. 155-190. Pls. 26-30. April,
1899.

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‘Y OF NATURAL HISTORY;

H ENTOMOPHTHOREA OF THE UNITED STATES.

By ROLAND THAXTER.

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VI. Tur EntromoryTooreArE OF THE UNITED STATES.

By Roxuanp THAXTER.

: Tue material upon which the followmg account is based was accumulated, for the
~ most part, during the seasons of 1886-7, from several localities in New England and in
a North Carolina, shiek were examined with such thoroughness as the limited time at my
- disposal would allow. The New England material was chiefly collected at Kittery
Point, Maine, the southernmost point in the state, and in the vicinity of Boston; while
the remainder is the result of two weeks botanizing in the alpine and sub-alpine region
of Mt. Washington, N. H. The more southern forms represent three principal localities
a in or near the western portion of North Carolina. Of these Cullowhee, 2400 ft. above

the sea, is the southernmost, having a flora of a distinctly southern type; while the two
_ others, Cranberry (3250 ft.) and Burbank (KE. Tennessee, 3500 ft.), have a climate and
ra not unlike that of the southern New England states. The eastern section of the
tet States is thus fairly well represented a so far as the localities which have been
: pended are concerned; yet it is scarcely necessary to remark that the forms obtained dur-
& ng a few weeks’ sojourn in each locality, in the course of general botanizing, can repre-
~ sent only in a fr agmentary way the Hntomophthoreae of this section of the country. The
im orms occurring in the more remote regions of North America are, moreover, as yet al-
most wholly unknown; and, although my observations have served to increase the num-
ber of American representatives from four previously recorded forms to the considerable
af nun ber hereafter enumerated, it cannot be supposed that the record is other than very
Ms m1 verfect. The present paper is therefore complete only in so far as I have endeavored
te © combine my own observations with those of previous students of the group in this
~ country and in Europe.

___ For this purpose the literature of the subject has been consulted as far as has been
: _ practicable, and a list of the papers that I have myself seen is appended to this memoir.

ft should be understood, however, that this list is not intended as a complete record of
that has been written upon the subject, and is merely given for convenience of refer-

oe in the text.

_ The Russian publications of Sorokin were kindly procured for me in St. Petersburg
Ir. Charles Eliot, and for some knowledge of their contents I am indebted to Mr. Ivan
Panin. For the privilege of examining the remaining papers, not contained in the Uni-
_-versity libraries in Cambridge, together with other invaluable assistance, I am indebted
5 to Professor Farlow, in whose hor atory the microscopic work upon my paper has been
for the most part done. To Miss Hapgood I owe certain extracts from the Polish of

IRS BOSTON SOC. NAT. HIST., VOL, IV. 20 (133)

~

134 ROLAND THAXTER ON THE

Nowakowski, and I am also indebted to Professor Farlow, Messrs. C. V. Riley, L. O.
Howard, Henry Edwards and A. F. Chatfield for several interesting specimens. To
Mr. C. W. Woodworth and Prof. 8. W. Williston I also owe certain entomological de-
terminations.

The plants that are to be considered in the present paper belong to a class which, al-
though made up of several groups differig widely from one another in their habit and
affinities, is yet, by reason of a peculiarity common to all its members, possessed of a
certain individuality of its own that renders it susceptible of a consideration apart from
all other forms of plant life. This peculiarity, by reason of which the class is usually
characterized as entomogenous or entomophytous, consists in an obligatory parasitism
upon insects, which, although in some instances it exists without apparent injury to the
insect host, is usually of such a nature as to cause its death; often resulting, especially
among noxious insects, in widespread mortality.

Although a few of the more common or conspicuous forms of entomophytous plants
had attracted the notice of botanists even in the last century, it was not until within
comparatively recent years that they began to be studied with any care, and the work
of Robin! is the first contribution of importance on the subject. This work still remains,
with two exceptions,” the only attempt that has been made to bring together all the known
forms of insect parasites; but since its publication very important contributions have been
made to our knowledge of the subject, through the medium of numerous scattered
papers.

My attention was first turned in this direction in the course of entomological studies
on the life-histories of certain insects; in the course of which I was often greatly annoyed
by losing large numbers of larvae and pupae through the agency of fungi. Haying by
this means and from other sources accumulated a certain amount of material, it was my
first intention to include in my paper all the entomogenous plants recorded from Amer-
ica; yet, owing to the many difficulties presented by the ascomycetous forms, involving
a careful study and comparison of more abundant material than I could command, as
well as by reason of the considerable additions to our Entomophthoreae resulting from
my observations, I have decided to confine myself for the present to the members of this
family, trusting to a future opportunity of extending my paper in conformity with my
original plan. In the meantime a brief summary of the more important groups may not
be out of place in this connection, and will be a fitting introduction to the more detailed
consideration of the Entomophthoreae which follows.

Summary of entomogenous plants.— Although the spiders and myriapods are not ex-
empt from the attack of peculiar vegetable parasites, the hexapod insects offer by far the
greater number of instances of this nature. Among the seven orders of the latter class
usually enumerated, the Neuroptera and Orthoptera are almost wholly free from such
attack; and, until recently, the first named order was considered wholly exempt in this
respect. Of the remaining orders the Lepidoptera and Diptera are apparently the great-
est sufferers; while the Hemiptera, Coleoptera and Hymenoptera are about equally af-

1C, Robin, J. ¢. that are known to form the bases of fungoid parasites,
2Sorokin, 7. c., C, and Gray, G. R: Notices of insects London, 1858.

.

is at.

ENTOMOPHTHOREAE OF THE UNITED STATES. 135

fected. Of the different stages of insects the imagines, larvae and pupae may all be
parasitized, and in some instances a single parasite may attack all these stages in one or
more species of the same or different orders; while in others it may confine itself to a
single stage or species.

Entomogenous plants may in a general way be referred to five principal groups: one
including the bacterial forms which produce disease in insects; a second represented by
certain entophytous algae; and three others all belonging to the fungi proper.

The first mentioned group, represented by the Bacteria, is chiefly of interest from an
economic, rather than from a botanical point of view, as the supposed cause of destruc-
tive epidemics among useful as well as noxious insects. Instances of this kind are pre-
sented by the disease known as flacherie so destructive to silk worms, and in affections
of a similar nature in other insects, where the “active principle” has, in some cases,
been traced to bacterial forms which have been considered sufficiently peculiar to receive
distinctive names. ‘The systematic study of the group is necessarily one of great diffi-
culty, and any opinion as to the validity of specific distinctions in such cases can only
be formed by specialists in this department; but from a practical standpoint the existence
of such affections promises to afford an important means of defence against noxious in-
sects.

The second group includes a small number of peculiar filamentous algae, represented by
Enterobryus and its allies, that live attached to the digestive tracts of certain myriapods
and coleopterous larvae. They are apparently nearly related to Oscillaria or Beggiatoa
among the Protophytes; but, owing to insufficient observations upon them, their exact af-
finities are unknown. ‘Their habit is probably one of commensalism, rather than of true
parasitism; the partially digested food of the host being absorbed directly from the di-
gestive tract.’

The fungoid parasites of insects are, as before mentioned, represented by three chief
groups: the Entomophthoreae, the Laboulbeniaceae and the entomogenous forms which
constitute the bulk of the genus Cordyceps. Since the first of these is to receive spe-
cial consideration hereafter, it need only be said that its members are closely allied to the
Mucorini among the Zygomycetes, and are entomogenous with few exceptions.

The Laboulbeniaceae constitute a small group of very peculiar and minute forms which
have been placed by DeBary among the doubtful Ascomycetes. Their parasitism is
an external one, which apparently results in little if any inconvenience to the host; each
individual being fixed by a pedicellate attachment to the legs, thorax or other portion of
the affected insect. Several genera on Diptera, Coleoptera, ete., are described by Pey-
ritsch? to whom we are principally indebted for our knowledge of the group, although the
first genus of the family (Laboulbenca) was described and figured by Robin.? The
single American representative thus far recorded has been described by Professor Peck
as Appendicularia entomophila, n.g. et sp.*

The pyrenomycetous genus Cordyceps affords by far the most conspicuous examples
of entomogenous plants, many of which are of large size, or brightly colored, and have

1See Leidy, Smiths. Contr. to Knowledge, v, pp. 1-67 p. 227 (1873): 72, 1, p. 377 (1875), plates.
(1853) and Robin 7. ¢., p. 395. 3]7.¢., p. 622, plates.
? Sitz. d. Akad. wiss. Wien., 64, 1, p. 441 (1871): 68, 1, 4 Peck, 38th Report, p. 95, with plate.

136 ROLAND THAXTER ON THE

therefore received more attention from earlier botanists. Their imperfect or “ Jsaria”
condition is familiar to all entomologists as a pest in breeding cages and puparia; al-
though the ascigerous condition is usually of rare occurrence. They attack all orders
of hexapod insects, larvae and pupae as well as imagines, and also certain spiders; often
producing what is vulgarly known as a “vegetable sprout” several inches in length.
A considerable number of American species are recorded; yet, owing to the lack of suffi-
ciently well-marked microscopic characters, as well as to the scarcity of good material
for study, the group presents many difficulties, as is usual in cases when too great re-
liance has been placed upon gross characters as a means of specific distinction.

In addition to the groups above mentioned there are several other isolated instances
of entomogenous fungi, among which should be mentioned the so-called Botrytis Bas-
stana which produces the disease known as Muscardine, so destructive to silk worms in
Europe and apparently identical with a similar form occurring in this country.

Facultative parasites of insects —In addition to the obligate parasites briefly enumer-
ated above, insects are often subject to the attack of numerous small moulds and bacteria
which are in no sense peculiar to them, although they may temporarily assume a habit
which is practically that of a true parasite, entering the living host and causing its
death. It seems also probable that one or two forms which are truly entomogenous are yet
saprophytes, as in the case of a certain Cordyceps (C. armeniaca) presumably growing
upon the remains of insects in the excrement of insectivorous birds, as well as the
members of the genus Basidiobolus hereafter mentioned, which occur upon the excre-
ment of frogs and lizards. DeBary has also pointed out that the species of Cordyceps
are normally partial saprophytes, since they attain their full development after the death
of the host; but whether wholly parasites or saprophytes, or parasites and saprophytes
combined, their peculiarity in growing naturally only upon insects or insect remains con-
stitutes them entomogenous, in the sense in which I use the term, to the exclusion of ©
such forms as Penicillium, Aspergillus, Cladosporium and the like; which, although they
may at times not only grow on insects, but become temporarily truly parasitic upon
them, are yet found in nature on a great variety of other substances. -

With this brief reference to entomogenous plants in general we may now turn to the
consideration in detail of the group which forms the subject of the present paper.

ENTOMOPHTHOREAE.

General characters—This family at present comprises several genera, the members
of which are not all entomogenous, though closely related structurally. They are dis- _
tinguished by the production of numerous hyphae of large diameter and fatty contents,
which, in the insect forms, ultimately emerge from the host in white masses of charac-
teristic appearance and produce at their extremities large conidial spores which are yio-
lently discharged into the air and propagate the disease. The common house-fly fungus
is perhaps the most familiar example of the kind, and no one can have failed to notice —
the affected flies in autumn or late summer adhering to looking-glasses or window-panes
surrounded by a smoky halo of discharged conidia. In addition to these conidia the

‘propagation of the fungus, after long periods of rest, may be provided for by the forma-

_ s

ENTOMOPHTHOREAE OF THE UNITED STATES. 137

.

tion of thick-walled resting spores adapted to withstand successfully the most unfavorable
conditions. These resting spores, which may be either sexual (zygospores), or asexual
(azygospores), finally germinate and produce conidia that are discharged in the usual
fashion and serve to infect fresh hosts. Such in brief is the general mode of develop-
ment in Hntomophthoreae; yet it is subject to so many variations and modifications in
the different genera and species that a detailed comparison of them is instructive as well
as necessary for a sufficient understanding of the family. I shall therefore consider each
stage among the /mpusae in some detail, having first briefly mentioned the more impor-
tant points of structure in the remaining genera. These genera are four in number:
Oompletoria, Conidiobolus, Basidiobolus and Massospora, the members of which, as al-
ready mentioned, are not all entomogenous.

The genus Completoria, which, as has been pointed out by Nowakowski and others,
should be placed among the Entomophthoreae, was discovered by Lohde (/. c.) in the pro-
thalli of ferns and has been subsequently more thoroughly investigated by Leitgeb (J. ¢.).
Its presence is indicated by brown spots upon the prothallus within the cells of which it
exists in the form of short thick hyphae, which spread from cell to cell by means of slen-
der projections. The latter penetrate the cell wall, which becomes modified around them
into a sheath-like structure, and having thus gained access to an adjoining cell con-
tinue their development at its expense. The two usual forms of reproduction, by means
of conidia and resting spores, are found in the genus and are of a very simple type.
When about to produce conidia the short thick hyphae or hyphal bodies, as they may be
termed for convenience, germinate sending up asexually fructifying hyphae or conidio-
phores which, after penctrating to the surface of the prothallus, become swollen at their
extremities and produce ovoid conidia which are discharged into the air. After their
discharge the conidia become pear-shaped, and the basal papilla of attachment to the
basidium, or swollen extremity of the conidiophore, is protruded as a hyaline append-
age (Nabel). ‘The conidia germinate and spread the disease by entering other pro-
thalli with which they may come in contact. The resting spores are formed within the
cells of the prothallus, and result from the mere contraction of the contents of the hy-
phal bodies, which become surrounded by a thick wall. According to Leitgeb, this
formation shows no indications whatever of a sexual origin, although his figures do not
seem to preclude such a possibility in view of what is at present known of sexual proc-
esses in the group. The germination and further development of these resting spores
have not as yet been observed. The genus is at present represented by a single species,
Completoria complens Lohde, and has been found and cultivated by Leitgeb upon pro-
thalli of numerous genera and species. It is at present unknown in this country. From
this comparatively simple form we may now pass to the consideration of one somewhat
more complicated, which is also parasitic upon another plant, in this instance a thallo-
phyte.

The genus Conidiobolus was accidentally discovered by Brefeld in connection with
his researches upon the Tremellini on which it is parasitic; and its discoverer, having
obtained spores from cultures in which it had appeared, was enabled by cultivating them
in nutritive solutions, to trace its development with the greatest completeness. The co-
nidia grow readily in a decoction of horse dung, forming a mass of branched and
rarely septate hyphae; which, having nearly exhausted the nutritive solution, become

138 ROLAND THAXTER ON THE

broken up, through the formation of partition walls, into numerous irregularly lobulated
fragments which correspond to hyphal bodies, as I use the term. These lobules appear
early in the development of the hyphae, in the form of irregularly swollen projections
from them; and mark the points of origin, even at an early stage, whence the conidio-
phores are subsequently to arise. Shortly after this general disintegration of the hy-
phae, single, simple conidiophores arise from each fragment, in number corresponding to
the swellings above described, and produce large, ovoid conidia which are discharged in
the usual way. The chief interest of the genus lies, however, in the formation of its rest-
ing spores, which seem to be of sexual origin. This formation of zygospores appears
as that of the conidia begins to disappear, so that both forms are at first developed side
by side, while eventually the conidial formation ceases entirely,— a circumstance which
seems to verify this author’s previously expressed opinion that an alternation of some
regularity exists between the appearance of the two types of reproduction. In the for-
mation of these zygospores, hyphae arise from swollen projections, similar to those
already described as being the origin of the conidiophores, which, after a variable devel-
ment, conjugate through the apposition of their swollen extremities, the contents of one
extremity uniting with that of its fellow through the absorption of the intervening
walls, and producing in one of them a thick-walled zygospore. Owing to a difference
in size of these conjugating extremities, Brefeld was inclined to place the family among
the Oomycetes; but the previous observations of Nowakowski' in Hmpusa, together
with more recent studies of the family, render this improbable. In from ten days to five
weeks after their formation, the resting spores were made to germinate; and sending out
one or more hyphae produced usually a single conidium resembling those characteristic
of the species. Of these, two are described: Conidiobolus utriculosus and C. minor,
neither of which has been observed in the United States.

The genus Basidiobolus, discovered by Hidam, is perhaps the most interesting of the
Entomophthoreae from the unusual differentiations which accompany its asexual as well
as sexual reproduction. Unlike other members of the group the species are wholly sa-
prophytic, occurring naturally upon the dung of frogs and lizards after evacuation; while
they may be readily cultivated in nutrient solutions similar to those employed by Brefeld
in his study of Conidiobolus. According to Hidam, the fungus is present in the digest-
ive tract, only in the form of spores or hyphal bodies which are dormant until they are
evacuated with the faeces upon which they subsequently develop, forming large color-
less hyphae with numerous cross partitions. These hyphae do not become broken up
into hyphal bodies before reproduction commences, except in so far as this condition
may be approached in cases similar to that figured by Hidam? where, in a concentrated
nutrient solution, the segments of the hyphae become rounded; but do not, however,
break apart as in Conidiobolus. In reproduction the hyphal segments may produce
slender single conidiophores which, rising vertically, become greatly swollen at their ex-
tremities. From the apex of this conidiophore the large conidium buds and, during its
formation, the swollen extremity which bears it becomes modified by the contraction and
thickening of its walls into a peculiar piece or basidiwm, which is discharged, together
with the conidium, by the explosion of the slender conidiophore.

DE Cows 211; 6s, Plex tian:

ENTOMOPHTHOREAE OF THE UNITED STATES. 139

The formation of zygospores is also quite peculiar, and always results from the conju-
gation of two adjacent cells in the same hypha, except in some instances where two co-
nidia may conjugate directly. In either case conjugation is preceded by the formation
of finger-like processes from either of the conjugating cells, which, arising opposite each
other, are usually closely applied. Conjugation, however, does not take place by means
of these processes which, at first sight, would suggest a Rhynchonema-like type; but by
the absorption of the partition wall between the conjugating cells and the direct passage
of the contents of one into the other. In this instance, as well as in Conidiobolus, the
cell in which the zygospore is to be formed is recognizable before conjugation by its
larger size. The function of the finger-like processes above mentioned seems wholly
connected with the division of the nuclei which pass into them and become divided in
two parts; the upper portion disappearing without becoming a new nucleus while the
lower passes as a nucleus into the zygospore. ‘lhe zygospores are of two varieties: one,
larger than the more common form, is very thick walled and covered by a peculiar brown
incrustation which renders it opaque; the smaller and more usual variety was made to
germinate in nutrient solutions and produced hyphae which developed the characteristic
conidia of the species.

Two genera remain to be mentioned: Tarichium of Cohn and Massospora Peck. The
former, as has been several times pointed out by writers on Entomophthoreae, is, with-
out doubt, merely the resting stage of some Hmpusa, the conidia of which are as yet
unknown. In Massospora, however, which has not, I believe, been previously referred
to the present family, we have a form quite peculiar, the near affinities of which cannot
be determined by reason of the absence of any knowledge concerning the formation of
its resting spores, or the germination of the multitudinous internal spores which char-
acterize the genus.

With this brief mention of the remaining genera we may now pass to a consideration
of the genus Hmpusa, which, with its subdivisions, includes only entomogenous forms.
I have preferred to consider these subdivisions as a whole under “mpusa as a matter of
convenience, as well as from the fact that [am not at present inclined to believe that
they have more than a subgeneric value; but my reasons for this course, as well as for
my use of the name Hmpusa in preference to Hntomophthora, may be better given here-
after when the principal morphological differences in the species have been touched
upon.

Tue Genus Empusa.

Infection and production of hyphal bodies —As has already been mentioned, infection
among entomogenous Entomophthoreae results from contact with a conidial spore which,
adhering to the insect host, enters its body by means of a hypha of germination. The
exact method of this entrance is hardly a subject for actual observation unless, perhaps,
in insects which, like many aphides, are semitransparent, and, owing to their soft integu-
ment, afford an easy entrance to the hypha at almost any portion of the body. In other
insects, more especially beetles, grasshoppers, ichneumons and the like, the horny integ-
ument must diminish considerably the chances of infection; and in such cases the stig-
mata or the thin membrane connecting the body segments and leg joints must be the

140 ROLAND THAXTER ON THE

principal points of entrance. Infection, resulting from the ingestion of spores with the
food, does not, I think, occur as is indicated by experiments with wood crickets which
will be mentioned under #. Grylli; and, as a rule, the digestive tract during life does
not seem to be penetrated by the fungus.

After the hypha of germination has entered the body of the host, it develops with some
rapidity at the expense of the softer tissues. This growth usually differs from that de-
seribed in Conidiobolus from the fact that, instead of producing a branched mycelium,
the hyphae multiply, not by branching and continuous growth, but by the formation of
what I have previously called hyphal bodies, which consist of short, thick fragments, of
very varied size and shape, that are continually reproduced by budding or division until
the insect is more or less completely filled with them. In some instances these hyphal
bodies have been observed as naked masses of protoplasm with an amoeboid movement,
as is stated to be the case in /. colorata; but in most instances a cell wall may be dem-
onstrated. In H. Grylli,at an early stage, the hyphal bodies may be seen loosely adher-
ing in clusters as aresult of continued budding; but more often in this and other species
they occur singly or in pairs. It is probable, however, that this mode of development is
subject to considerable variation and that in some instances a mycelium may be produced
directly, after the entrance of the germinating hypha. I have been unsuccessful in en-
deavoring to cultivate conidia in sterilized solutions; although, by employing a drop of
water in which numerous aphides had been crushed, I was enabled to obtain a fairly
vigorous growth from the conidia of /. aphidis. In this case the germinating hypha
branched in all directions, forming a considerable mycelium with numerous septa; but,
owing to the lack of nutriment as well as to the presence of bacteria, the hyphae soon
became much attenuated and finally died. DeBary’ states that this production of a
mycelium as a first result of infection occurs in EH. ovispora, H. curvispora and H.
sphaerosperma (radicans) ; but, according to Nowakowski, in his summary of the Em-
pusae; the first two are not thus characterized, while my own observations of 1. sphae-_
rosperma do not bear out his statement that the “fungus growth” within the host is
filamentous in all cases. It seems not improbable that both forms of development may
occur under different conditions; but, however this may be, the termination of the first
or merely vegetative condition of the fungus consists in the production of a mass of
hyphal bodies which fill the host more or less completely; and in no instance, I believe,
is this stage or its equivalent omitted by the direct growth of the original hyphae into
conidiophores. On this assumption, in cases where a direct mycelial growth follows
the entrance of the hypha of germination, if indeed such instances occur, this myce-
lium must fall to pieces into hyphal bodies, before the commencement of growth the
direct object of which is reproduction, in a fashion resembling that above described at a
similar stage in Conzdiobolus.

The hyphal bodies, the production of which usually marks the end of any appropria-
tion of nourishment from the host and generally occurs at about the time when the host
has ceased to live, are in many cases somewhat different from those which have previ-
ously characterized the fungus and often possess great regularity, both in size and
shape, closely resembling spores. In /. Fresenii, for example, the original hyphal bodies

1Vergl. Morphol. d. Pilze, ete. TG. 45, panne

ENTOMOPHTHOREAE OF THE UNITED STATES. 141

are such as are represented in figs. 106-108, while fig. 127 shows examples of those
which precede the spore formation and are derived from them. In other cases, the ulti-
mate hyphal bodies may be very irregular in size and shape. In all instances, they contain
a highly concentrated fatty protoplasm and are capable of subsequent and often very
extended development.

Having reached this condition by the production of a mass of hyphal bodies, the fun-
gus, under favorable conditions of temperature and moisture, may proceed at once to
the completion of its development; but if these conditions are absent, a resting or
chlamydosporic condition supervenes, in which the contents of each hyphal body be-
come surrounded by a single wall of variable thickness according to the duration of
this enforced resting stage. In this manner, the fungus may remain dormant for a
considerable period until the presentation of proper conditions for further growth. How
long the chlamydospores may live, I am unable to say; but I have observed their germi-
nation after several weeks, and they probably retain their vitality for a much longer
period, and may perhaps hibernate under certain circumstances. They form a very con-
venient means for the cultivation of Empusae in water, in which they proceed at once to
the formation of conidia or of resting spores. The period from first infection to the
formation of chlamydospores or hyphal bodies, prior to the commencement of the repro-
ductive growth, varies according to the host. In very minute and ephemeral insects,
such as many gnats that are commonly attacked, the period must necessarily be short,
not exceeding two or three days; but in cases where I have been enabled to observe this
period, which has been unfortunately only in connection with the larger hosts, such as
flies and caterpillars, it varies from six to twelve days.

Germination of the hyphal bodies and chlamydospores.—HUaving appropriated the
whole or the greater portion of the nourishment afforded by the host, the fungus is now
ready to expend it in the second or reproductive stage of its growth. Under the influ-
ence of a moist atmosphere and a sufficiently high temperature, the hyphal bodies
“oerminate” with great rapidity. The amount of moisture needed to produce this ger-
mination is variable in different forms. In the common house-fly fungus (7. muscae),
for instance, a slight change in the amount of atmospheric moisture is sufficient to pro-

duce conidial formation and discharge. This is very noticeable on the seashore, where
slight changes of the wind on or off the water produce a very rapid and noticeable ef-
fect upon flies thus parasitized when observed in the ordinary atmosphere of the house.
In other instances, more especially in those species which, unlike the house-fly fungus, are
characterized in their conidial reproduction by a considerable external growth of hyphae,
amuch greater degree of moisture is a necessity. Hxtreme cases of this kind are found
in species such as #7. conica or H. sepulchralis which occur only in very moist situa-
tions.

In germinating, each hyphal body or chlamydospore sends out one or more hyphae which
grow with great rapidity; but the manner of this germination, together with the subse-
quent development of the resulting hyphae, varies considerably in different species and
under different condition. In the simplest case a single hypha thus produced may grow
directly to the outer air and then produce a single conidium or set of conidia, according
to the type peculiar to its conidiophores. In other cases, a single primary hypha may

MEMOIRS BOSTON SOC. NAT. HIST., VOL IV. 21

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142 ROLAND THAXTER ON THE

branch indefinitely, each ultimate branch becoming a conidiophore similar to those of the
more simple case just mentioned. This usually occurs where the conditions of growth
have been very favorable and may be found side by side with the more simple form.

Although the number of germinating hyphae developed from a single hyphal body is
usually small, not as a rule exceeding one or two, certain instances occur in which the
number is considerable. In #. conglomerata, for example, as described by Sorokin, long
hyphal bodies are found which germinate in all directions and are not unlike, in this re-_
spect, the hyphal bodies previously mentioned in Conidiobolus. These hyphae subse-
quently branch and anastomose, forming a coherent mass which Sorokin has termed a
stroma, and on which he has based a classification of H’mpusae into “Stromaticae” and
“ Astromaticae.” It is probable, however, that this condition is interchangeable with the
more ordinary form, since in some specimens for instance of #. apiculatus, I have found
well marked stromata, while in others the direct development of the conidiophores from
hyphal bodies has been distinctly traceable.

The most singular modification of this kind, however, occurs in . aphidis and virescens
which are the only species thus far in which it has come under my observation. Here
we have a body which appears to be of the same nature as the hyphal bodies in other
species, of regular spherical form and with a highly refractive fatty contents, from which,
soon after the death of the host, hyphae begin to germinate in all directions and in in-
credible numbers, in a fashion that reminds one of a head of Aspergillus (figs. 239 and
261). The hyphae thus produced then branch and divide, becoming separated into a
mass of irregular, short, contorted hyphae which fill the host and distend its body. This
breaking to pieces of hyphae produced from hyphal bodies also is found in species where
the usual type of germination occurs: as in #. muscae, in which, just before the emer-
gence of the conidiophores, the body cavity contains a mass of irregular short hyphae
together with germinating hyphal bodies.

Formation of conidiophores.—The germination of the hyphal bodies results either in
the production of sexual or asexual resting spores (zygo- or azygospores); or of coni-
diophores bearing conidia. In the latter instance hyphae, arising directly or indirectly
from the hyphal bodies, grow rapidly outwards, burst through the less resistent por-
tions of the host’s integument in spongy masses, in most instances of a livid white color.
These masses sometimes vary to pale or bright green or dull olive, even in forms where
their normal color is white; and there is considerable variation in their general appear-
ance according to the species or to the conditions of their development. In some cases,
they barely project beyond the body of the host and are confined to the points of emer-
gence which are generally afforded by the thin intersegmental membranes through which
they project in cushion-like rings as in #. muscae. In other eases, the external growth
may be more extended and the masses may coalesce so as to cover the whole body with
a continuous layer of conidiophores which may form a mass several times as large as
the insect from which it springs.

In the first and more simple case, where there is little external fungus growth, the
cushion-like masses are usually formed by simple conidiophores (fig. 1) which, although
each may be derived in common with many others from the same hyphal body, are yet
ultimately simple, producing few or no branches outside the host’s body and giving rise

—_——- 6s

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ENTOMOPHTHOREAE OF THE UNITED STATES. 143

to a single conidium. In the second instance, where the external growth is greater, a
different type usually occurs in the conidiophores. Not only is the external branching
very considerable, but the ultimate divisions of each conidiophore are arranged in a co-
rymbose or digitate fashion, as in figs. 202 and 220. ‘This occurrence of simple and
compound conidiophores in different species has led to the generic separation of the two
groups; yet the distinction is by no means absolute, and intermediate forms occur, as in
EH. culicis, LH. apiculatus and a few additional species. The converse is also true, and
simple conidiophores are very commonly found in species where the type is usually com-
pound. As has been already remarked, the growth of conidiophores is very rapid under
favorable conditions; and an insect containing hyphal bodies, if placed in a damp, warm
atmosphere, may give rise to the characteristic white masses in a few hours. Soon after
the appearance of these masses the production of conidia commences, and this brings
us to the next step in the conidial development.

Formation and discharge of the conidia—The terminal portion of the conidiophore,
whether this be simple or one of several digitations, is termed the basidium and is usu-
ally swollen to a greater or less extent. From the apex of this basidium, which is ho-
mologous with similar structures occurring among the Mucorini, the conidium, or more
properly the mother cell of the conidium, is formed by budding. This bud increases
at the expense of a portion of the contents of the basidium, until it has attained very
nearly the normal shape and dimensions of the conidium; when it becomes separated
from the basidium by a cross partition, which forms at first a horizontal plane of separa-
tion between the two and is homologous with the columella of the Mucors. Within the
mother cell thus formed is developed a single conidial spore, the walls of which are nor-
mally in close apposition to those of its containing cell, which must thus be considered
asporangium reduced to its simplest terms and modified to combine economy of material
with a judicious dissemination. The resemblance to a one-spored sporangium is clearly
seen in cases where, through the absorption of water by osmosis, the wall of the mother
cell becomes separated from that of the conidium; a phenomenon which is very com-
monly seen after, or even before, the discharge of the conidium, and is sometimes carried
to such an extent that the conidium may be seen floating free in a large spherical
mother cell (fig. 321).

When the conidium is fully developed, and even previous to this, the contents of the
spore, as well as of the basidium, begin to expand through the absorption of water.
At first, as a rule, the contents of the basidium exert the greater of the two forces thus
produced; perhaps owing to the fact that a more rapid absorption of water is possible
through its single wall than through the double wall of the conidium. For this reason,
the columella is at first forced outwards into the conidium'towards which its convexity
is thus turned. In some instances, especially in cases where the basidia are large and
strong, this condition of things may continue until the discharge of the conidium.
Such is apparently the explanation of the appearance figured by Nowakowski' which is
referred to by Hidam’ as a mechanism for discharge, very different from that usually

found in Empusae. I think, however, that this will prove to be only an extreme case of

the nature just described. In my own experience I have observed this appearance only
']..c. B, Pl. xt, fig. 82, etc. ate Cr De 1S.

144 ROLAND THAXTER ON THE

infrequently in the species referred to, #. Grylli, and in allied forms (fig. 83). — It
should be noted that contraction of the spore contents from any cause might also produce
the same condition. In by far the majority of cases, the contents of the conidium, be-
ing more dense than that of the basidium, finally exert a greater pressure and forces the
columella back into the basidium, thus reversing its former position. The sum of these
opposing forces is very considerable, and as a natural result of their action a rupture of
the wall ensues at the point where they are opposed, that is, in a circle round the base
of the mother cell. This circle of rupture is usually very evident in discharged conidia,
being indicated by a slightly ragged projection which forms a ring at the base of the
papilla (fig. 85). As a result of this rupture, the conidium is discharged violently
into the air, often to a considerable distance. The columella commonly remains un-
broken by this discharge, although it is often greatly stretched and hangs from the ba-
sidium as a tongue-like projection. In other instances it may be accidentally broken
or this rupture may be normally connected with the discharge. In the latter case, a por-
tion of the protoplasm from the basidium is discharged with the spore and serves to
fix it to any object with which it may come in contact.

The presence or absence of a columella in different species has been made a point of
structural difference to which more weight has, I think, been given than is justified by
the facts. The assumption that a columella exists and is wholly or partially destroyed
by the discharge of protoplasm above alluded to, in cases like #. muscae for example,
seems to me at least as warrantable as the apparently needless assumption of the absence
of so characteristic a structure. Moreover, the presence of a ruptured. columella is often
indicated even in #. muscae by the numerous shreds that may be seen adhering to the
basidium after discharge (fig. 2).

The conidia and their germination.—The conidia in their normal condition are of yvari-
ous size and form, often varying considerably in the same species. The extremes of shape
are well represented by the nearly spherical spores of 1. muscae and the slender tapering
form of #. gracilis. In size they vary from about 10# in length to 75+ or over. They
are usually hyaline, rarely slightly colored, with a fine granular contents; or, more com-
monly, contain coarsely granular protoplasm with large fat globules. In many instances,
these fatty bodies are so regular in size and shape that the conidia resemble asci filled with
spores; a fact which probably accounts for the statement “Flocci fertiles intus sporidiis
elobosis referti” in a description of what seems undoubtedly an Hmpusa, by Fries.1 The
common occurrence, also, of very large single oil globules seems to have caused a similar
error. The walls of the conidium are, so far as known, always smooth, without spines
or similar modifications, and possess an adhesive quality which serves to attach them
readily to any object, even when their discharge is unaccompanied by the mass of pro-
toplasm above described. The basal portion of the spore is always more or less papil-
late, the papilla being in reality that portion of the spore proper which projects from
within the mother cell, from which it is distinguished by the ring of dehiscence.

The conidium when discharged, if by chance it has come in contact with a suitable
host, adheres to it, and sends out a hypha of germination which enters its body as pre-
viously described. When placed in water the conidia give rise to one or more hyphae

LRGs

ENTOMOPHTHOREAE OF THE UNITED STATES. 145

which branch and elongate, growing constantly more attenuated, their protoplasmic con-
tents becoming separated by successive cross partitions from the empty hyphae left behind
(fig. 240). It may here be mentioned that this separation by cross partitions is common
in the general growth of the fungus. The hyphae produced thus from conidia have the
usual characteristics: a granular protoplasmic contents which often shows a very notice-
able streaming motion, and contains large oil globules and a hyaline wall. The power
of germination lasts, according to Brefeld, at most only a week, or slightly more in
#. radicans (£2. sphaerosperma) ; but in my own experience I have found the period
usually much shorter than this. he period is in all probability very variable; spores
that have been formed under unfavorable conditions being better able to withstand simi-
lar conditions: the endurance of the spores, moreover, varies with different species. As a
rule, germination takes place very soon after discharge, and if the conidium has neither
fallen upon a proper host nor upon a wet surface it proceeds to form

Secondary conidia.—The secondary conidium is a provision for further dissemination
in case the primary spore has fallen on a substance unsuited to its proper development.
The most common method of formation consists in the production of a hypha of vari-
able length, which, growing vertically upwards, becomes swollen at its extremity into a
basidium, and produces a conidium similar to that whence it is derived. This is dis-
charged in the usual fashion, and may in turn produce tertiary, etc., conidia, in a similar

yay, until its vitality is exhausted or it has found a suitable lodgment. The conidio-
phore formed in this process is usually simple, even if the type from which it was de-
rived is digitate; yet I have seen, in a case where numerous spores had been discharged
upon wet moss, that the hyphae arising from them united to form a mass of conidio-
phores of the digitate type peculiar to the species.

Although the form of secondary conidium just described is most commonly found,
and is apparently the normal type in all species under favorable conditions, it is subject
to several interesting variations that are dependent, for the most part, upon an insufficient
supply of moisture. The first of these consists in the production of a secondary conid-
ium quite different from the primary, either by direct budding from it (fig. 9), or borne
upon a short hypha of germination (fig. 362). These conidia are also discharged; but
are apparently better suited to resist unfavorable conditions than the ordinary ones, and.
probably retain their power of germination much longer. ‘The most singular modifica-
tion, however, is presented by a few species allied to HZ. sphaerosperma and H. Presenii.
Tn these forms and their allies, when the conditions of moisture are unfavorable for the
ordinary process, a long, slender, capillary conidiophore is produced, on the end of which
is borne a peculiar secondary conidium differing still more widely from the parent spore
than in the case just mentioned.

These secondary conidia (figs. 157, 191, ete.) are, with one exception, nearly almond-
shaped, with noticeably thick walls, and are not discharged. Whether they ever produce
tertiary spores similar to the primary ones, I have been unable to determine; but the for-
mation from them of tertiary conidia similar to themselves is not uncommon. They may
often be seen germinating by means of an irregular hypha which, beginning as a drop-
like protuberance from the apex of the spore (fig. 119), may grow to a considerable
length (fig. 122). Hidam, in his paper on Basidiobolus (Pl. 9, fig. 16), figures a mode

146 ROLAND THAXTER ON THE

of germination in this genus of a related type; but as the author describes the swollen
extremity of the conidiophore as a basidium, the similarity is not so striking as a com-
parison of this with fig. 119, for example, in the present paper, would lead one to infer.

Cystidia and rhizoids—Before leaving the conidia and conidiophores, two additional
structures must be mentioned, which are of some importance morphologically. These are
the so-called cystidia, or paraphyses as they have been called; and a modification of cer-
tain hyphae, known as rhizoids, which serve to attach the host to the substratum on
which it rests. The cystidia are usually simple hyphae, exceeding the conidiophores in
size, and projecting beyond them, often to a considerable distance. In some instances
they are very large (fig. 306), and readily seen with the naked eye; while in others they
do not differ from the conidiophores. They are not, I think, homologues of paraphyses in
other fungi, and their office is unknown; unless, perhaps, they may be considered as rhi-
zoids which are functionless from their position; an explanation which seems to me very
probable. A modification of the paraphyses should be mentioned which occurs in Z.
echinospora, a species in which, contrary to the usual type, the zygospores are very com-
monly produced externally. In this case, when the sporophores have emerged from the
host, certain of their number may be seen projecting beyond the rest (fig. 297). While
the process of spore formation is going on, these hyphae grow rapidly, forming ultimately
a delicate network about the mass of mature zygospores.

The hyphae of attachment, or rhizoids as they may be conveniently termed, consist of
hyphae which, growing from the lower and outer portions of the fungus mass, attach
themselves to the substratum upon which the host rests and serve to hold it firmly in
position. The rhizoids may be simple or variously branched, and their termination may
be variously modified into an expanded “sucker” (fig. 249). They do not, I think, enter
into soft substances, and their adhesion is apparently due to the presence of a viscous
secretion. They are produced with great rapidity, appearing even before the host is dead,
and increasing in number with the appearance of the conidiophores. Rhizoids are con-
fined to certain species, and generally accompany the digitate type of conidiophores;
their presence should not, however, in my opinion, be considered of any importance as a
generic distinction.

It is now necessary to return once more to the condition in which we find the host
filled with chlamydospores, or hyphal bodies, in order to examine the phenomena con-
nected with the

Formation of zygospores and azygospores——As has been previously remarked, the
germination of the hyphal bodies or chlamydospores may result in the production of
conidia above described; or may lead to the formation of spores called resting spores, of
a very different nature, and adapted to withstand successfully conditions that would prove
fatal to the conidia in a short time. The passage to this resting condition may be accom-
plished by a wholly non-sexual process, in which case the resulting spore has been termed
an azygospore, or by sexual union of a type similar to that found in the Mucorini. The
spores thus formed are usually of large size, spherical with one exception; with ahighly
refractive fatty contents; surrounded by triple walls, the outer thin and representing the
wall of the mother cell, the second much thicker, and the inmost usually as thick as
or thicker than the other two combined.

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ENTOMOPHTHOREAE OF THE UNITED STATES. 147

The simplest process by which azygospores are formed is presented by the case in
which the contents of a hyphal body become directly converted into a resting spore,
usually contracting somewhat and surrounding itself with two walls, the normal third
wall being represented by that of the hyphal body, within which the spore may be en-
tirely free, or to which it may be closely applied. A modification of this process occurs
sometimes in the case of chlamydospores, which may be transformed directly into azyg-
ospores by the deposition of a third inner wall.

Azygospores may also be formed in a variety of ways from hyphae of germination aris-
ing from chlamydospores or hyphal bodies, or not uncommonly by direct lateral budding
from them. In the first case the azygospore may be terminal (fig. 40), at the apex of a
hypha of greater or less length, or may bud laterally. This process, which may be read-
ily seen by cultivating chlamydospores in water, resembles at first the analogous forma-
tion of conidia; the end of the hypha, however, does not produce a bud, but becomes
swollen into a mother cell, which is not separated from the hypha by a cross partition,
and within which the double-walled spore is formed. Still another method consists in
the production of azygospores interstitially (fig. 81), which is common in certain species
and leads to the occurrence of spores having very irregular shapes.

These in general are the more common types of azygosporic formation, of which there
are numerous slight modifications. Where true zygospores are formed, a considerable
amount of variation is exhibited in the process as it occurs in different species; and al-
though the sexual nature of the spore is beyond question in some instances, it is not so
well marked in others, and may, as Nowakowski has suggested, represent a transitional
form from the truly sexual to the wholly asexual processes. Such instances are found
in H. sphaerosperma, a species in which, according to Brefeld, the production of resting
spores follows the septation and anastomosis of a mass of hyphae filling the host, the
spores being produced laterally from these hyphae without regard to the points of an-
astomosis. In my own experience I have observed something of this sort in the legs
of insects attacked by H. sphaerosperma and its near ally EL. occidentalis; but in the
bodies of the hosts examined, which, it should be remarked, were of a very different na-
ture from those (Pieris larvae) studied by Brefeld, I found only short, contorted hyphae
producing spores apparently in a wholly asexual manner (fig. 217), but associated with
them, numerous instances where the budding spore was directly associated with a cross-
putition or a slight lip-like fold indicating the previous existence of such a partition
(figs. 214-216). Whether spores thus formed should be called zygospores seems at least
doubtful, and the partitions described may indicate merely the ordinary division of the
hyphae. Ina very few cases, however, I have, in these two species, seen a process as well
marked as that represented in fig. 197, occurring in the legs of certain hosts where, as a
rule, the hyphae attain a considerable length. This certainly looks like true conjuga-
tion, and may lead us to cases where the presence of a sexual union is hardly to be ques-
tioned. The first instance of the latter class discovered among the Entomophthoreae
is that described by Nowakowski' in his three new species, /’. conica, EL’. ovispora and
Ei. curvispora. In this type we have hyphae, within or without the body of the host,
producing lateral outgrowths at opposite points of two different hyphae, which meet

ls C2, As

148 ROLAND THAXTER ON THE

midway between the two conjugating cells in a fashion analogous to the similar process
in Spirogyra. The intervening walls between these two gametes, or conjugating out-
growths, are then absorbed and a mingling of their contents ensues. A bud then appears
(fig. 322) on one or both the gametes, which increases rapidly, as a rule appropriating
the entire contents of each conjugating cell to form the zygospore. A septation of the
hyphae above and below the point of conjugation is often seen, but is not invariable,
resembling in this respect the similar process in Conidiobolus previously described. It
may be mentioned, in passing, that the chief distinction between the two rests on the
fact that here we have a zygospore formed by budding, while in Conidiobolus the spore
is produced directly within one of the conjugating cells. In this, as in other cases, the
empty hyphae disappear rapidly after the zygospores have been formed; a circumstance
which, together with the rapidity of the process as a whole, accounts for the infrequency
with which conjugation in Hmpusae can be observed. In one case, however (Z. rhizo-
spora), the hyphae after conjugation become brown and horny, holding the spores firmly
in a spongy mass (fig. 374); but even here the process of conjugation can only be seen
during a short period, while the spore is developing, owing to the subsequent contraction
and distortion of the hyphae.

In #. echinospora, in which the zygospores are often external, a modification of this
Spirogyra-like process is found, which deserves to be mentioned. Here (figs. 298-302),
we have a conjugation taking place between two filaments in a manner similar to that
described above; but, instead of arising by budding from one of the gametes or in their
immediate vicinity, the spore commonly develops as a terminal swelling from the end of
one of the conjugating hyphae.

Tn addition to these types of conjugation, a singular form, not, I believe, noticed hith-
erto in Entomophthoreae, occurs in H. Hreseni. It is,as far as I have observed, invari-
able in this species and is never associated, as is usually the case, with the production of
azygospores. The hyphal bodies, as they occur in the host just prior to the production
of conidia or zygospores, are almost perfectly spherical and very uniform; and are de-
rived from large, shapeless bodies which have the appearance of naked protoplasm. The
spherical hyphal bodies lying side by side within the host proceed to conjugate in a man-
ner indicated in the succession of figures 127 to 135. A slight projection first appears
from the upper inner end of either hyphal body (fig. 128). These projections soon
meet midway between the hyphal bodies (fig. 129), after which a bud begins to rise di-
rectly above their point of union (fig. 130). The contents of both bodies pass into this
bud, forming the mother cell of an elliptical zygospore which, I believe, affords the only
known exception to the usual spherical shape. After the spore is mature, the two hyphal
bodies usually persist for some time as bladder-like appendages (figs. 135-136), which
slowly disappear (figs. 187-140).

This is certainly a very simple process, yet it demonstrates I think, more clearly than
has yet been possible among Entomophthoreae the existence of an undoubtedly sexual
process of a distinctly zygosporic type. In Conidiobolus, Basidiobolus, and even in the
examples from Hmpusa previously given, there is usually a more or less marked differ-—
ence in the size of the gametes, which, in the first-named genus, led Brefeld to consider
the family as belonging to the Oosporeae; but, in the present instance, we have the ga-

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’

ty

ENTOMOPHTHOREAE OF THE UNITED STATES. 149

metes exactly alike, and in addition to this a process of development in the zygospore
similar to that occurring among the Mucorini in Pptocephalis. The regularity of this
process, and of the resulting zygospores, is worthy of mention; and although the hyphal
bodies are collected in an indiscriminate mass, the details of the process never show the
slightest variation from that described above.

Before leaving the subject of conjugation in Empusae, a singular method, by which
the resting spores of #. Grylli are often formed, must be described. This species is re-
markable for the great variety it exhibits in the details of the formation of its azygo-
spores; but in certain cases it seems not impossible that even in this species we may have
true conjugation of a type quite different from those previously described. The suc-
cessive figures, 31 to 35, indicate the nature of this process. In the first place we have,
before reproduction of either type, a condition characterized by the presence of irregu-
lar, rounded hyphal bodies of various size and shape (fig. 31). Instead of producing an
azygospore by any of the methods above described, one of these bodies may become
septate by the formation of a median cross partition (fig. 32). An elevation of the cell
wall presently appears around the hyphal body, between the cells thus formed, which
develops into a two-lipped fold (figs. 33 and 34). The partition between these two cells
is then apparently absorbed, for the contents of one gradually pass into the other to form
a “zygospore” (fig. 35). A variation of this process is found in the similar division of
the swollen extremity of a hypha (figs. 38-39) the lip-like folds in each being quite
peculiar. In many cases the formation of a resting spore is not accomplished by a sin-
gle division and subsequent union; but only results after a succession of oblique divis-
ions always accompanied by the lip-like folds, as in figs. 36 and 37. Spores of this kind
are usually characterized by their flattened bases, and in some instances two such spores
may be formed, one in either cell of the divided hyphal body, as often occurs in other
conjugating cells. Whether this is in reality a form of conjugation, I do not feel pre-
pared to say; and careful observations, by means of cultivations of the hyphal bodies,
are much to be desired. This process may in a measure explain the appearance previ-
ously alluded to (p. 147) and represented in figs. 214-216. Here there is no production
of a lip-like fold, yet it seems not impossible that in such cases a short hypha may have
divided and conjugated with itself, so to speak; the zygospore arising as a lateral bud
instead of developing directly within one of the divisions. Such an explanation may
seem somewhat far-fetched, yet the division of a hypha and subsequent conjugation with

_ itself are practically what occurs even in Basidiobolus.

The mature azygospores as well as the zygospores in all known species are, with the
exception of H. Hresenii, spherical in shape; and in the majority of cases are indistin-
guishable in the different species, except by slight variations of size. There are, how-
ever, three notable exceptions to this rule. ‘The spores of TVarichiwm megaspermum
Cohn? are characterized by a deep brown outer wall, or epispore, which is marked by
sinuous reticulations. In Z. echinospora (figs. 8303-305), the epispore develops numerous
sharp spines which separate it from all other known species; while in /. r/:zospora the
brownish spore is held by numerous rhizoid-like outgrowths from its base (figs. 374—
375). A dark brown epispore seems also characteristic of H. calliphorae Giard (2.

muscivora Schroeter).
lees a.

MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 22

150 ROLAND THAXTER ON THE

In my own experience, I have never observed the germination of resting spores in any
instance, although I have continued cultivations of them in water for upwards of three
months. I have not, however, had an opportunity of adopting the plan suggested by
Eidam of cultivating them in nutritive solutions, and a trial of this method might lead
to more satisfactory results. A germination of the resting spores of certain species is
reported by Nowakowski, Sorokin and Krasilstchik; and the first-named author states
that such spores placed in water in the autumn germinate during the following spring.
I have, however, seen no account of successful cultures of this nature unless it exists
in the text of Nowakowski. The description given by Krasilstchik of a species (.
uvella), in which he obtained a germination in four days, seems hardly reconcilable with
the facts as known in other genera. From analogy with Basidiobolus and Conidiobolus,
it is not to be questioned that the resting spores germinate, as in these cases, producing
the usual conidia; but whether this has been determined by actual experiment, I am un-
able to say. The period of rest before germination is probably very variable, and its
primary object is, of course, to afford a means of hibernation, or of withstanding simi-
lar protracted conditions unfavorable to development, and of long duration. Although
a single season is probably the normal period of this resting state, it has been suggested
by Brefeld that it may be extended over more than one season, thus allowing the insect
host to recover from the effects of Hmpusa epidemics.

The causes which induce the formation of resting spores can be explained with as
little satisfaction among Empusae as in other similar cases. The observations of Brefeld
in his experiments with 7. sphaerosperma Fres. (2. radicans Bref.), which indicated
that their production takes place towards the end of the season, gradually supplanting
the conidial form, are not corroborated by my own experience. ‘This, at least, does not
seem to be the course followed in the natural development of the fungus out-of-doors;
since the examination of some thousand or more of specimens shows that as a rule the.
relative number of individuals of a given species, which contain resting spores, remains
about the same from the middle of June to the middle of October. Whether the pro-.
duction of resting spores bears any relation to the number of previous generations of
conidia is a matter to be determined only by careful and repeated cultures in different.
cases. None of the remaining causes usually assigned as inducing zygosporic forma-
tion have any apparent influence in the present instance. But here also repeated experi-
ments in different cases, under known and variable conditions of moisture, temperature
and nutrition, are necessary to determine whether variation in these respects seems to
have any definite connection with the kind of spores produced.

The hosts of Empusae include representatives from all the hexapod orders; but among
them the Diptera are the greatest sufferers, at least in so far as the number of Empu-
sae which prey upon them is concerned. The Hemiptera come next, followed by the
Lepidoptera and Coleoptera; while the Neuroptera, [tymenoptera and Orthoptera are
about equally affected, and are attacked by two or three species, only, in each instance.
The liability to infection is shared by both larvae and pupae as well as_by imagines,
although the latter are most commonly affected. In insects where the larvae and pupae
differ but slightly from the imago, both these stages are equally susceptible to the dis-
ease. Mr. L. O. Howard has also shown me specimens of H#. Grylli that had devel-

ne

ENTOMOPHTHOREAE OF TITE UNITED STATES. 15]

oped upon the common web worm (//yphantria textor) after pupation; but this oceur-
rence is certainly unusual. Among Lepidoptera, I have been surprised to find the
imagines attacked in numerous instances, a fact, I believe, not hitherto observed; and
one species (2. geometralis) seems peculiar to them. Geometridae, Noctuidae and Ti-
neidae may be affected, and I have even found the common sulphur butterfly (Colias
philodice) thus attacked. The species or family of the host has hitherto been generally
considered a means of determining the species of Hmpusa, in most cases, with some
accuracy; yet my observations have shown that this is by no means the case and _ that
specific distinctions, based largely upon the character of the host, are of little value.
The variety of hosts attacked by a single species is sometimes very great, perhaps in no
instance more so than in LZ. sphaerosperma. Lhave specimens of this form upon the larva
of Pieris, on the imago of Colias philodice, Diptera of several families and genera,
Phytonomus larvae (Coleoptera), the common rose-leaf hopper ( Typhlocyba) and Aphis
(Ilemiptera), on ichneumons of several genera and a small bee (Hymenoptera), and on
a species of Thrips (Thripidae), while in Europe it is also recorded on Limnophilus
(Neuroptera). With such a diversity possible in the hosts, it is obviously unsafe to de-
scribe, as new species, forms without peculiar characters of their own, merely because
they occur in a new host, or to give any considerable specific weight to the character of
the host in support of slight variations in the shape of the conidia or the size of the
resting spores.

In certain instances, where several Empusae were found together, I have noticed two
species developed upon a single host; for example, 2. Aphidis and HL. Fresenii, as well
as HL. conica and H. papillata; H. gracilis and LE. variabilis; FH. lageniformis and LH.
occidentalis. It is, therefore, not always safe, where such proximity exists, to refer the
resting spores that may occur in connection with conidia to the same species of H’m-
pusa.

The habitat of Empusae is various, one of the most productive localities being the
margins of brooks in shady woods. Certain species are found only in such situations, ad-
hering to wet substances, such as moss, logs, stones, ete., in the water or along its mar-
gin; a constant supply of moisture being apparently necessary for their development.
In other cases dryer situations are preferred, and the fungus readily withstands the al-
ternate dryness and moisture consequent upon the variations of weather, producing its
conidia repeatedly, whenever the atmosphere is sufficiently moist, until the conidiophores
are exhausted. Many hosts, before death, seek conspicuous positions by crawling up-
wards on grass, or other substances, whence the conidia are discharged over a consider-
able area. Perhaps the favorite pusition assumed by hosts before death is upon the
under side of leaves in shady situations in woods or about houses, where a careful search
during wet weather seldom fails to disclose numerous specimens. I have noticed only
one species which occurs on flowers attractive to insects, namely H. Muscae; which, al-
though common in all parts of houses, I have only seen in nature on the flowers of Sol-
idago and eextet-certain Umbelliferae.

Miscellaneous notes—In collecting Empusae I have found that, as a rule, fogg
weather is the most favorable for the purpose, since they are more conspicuous when
distended by moisture. A shallow tin box, partly filled with moist Sphagnum, is a con-

152 ROLAND THAXTER ON THE

venient receptacle for specimens; and the latter should be kept separate. In the labora-
tory each specimen should be inverted over a slide or cover in a moist chamber, until a
sufficient number of conidia have been discharged, when it may be dried for the herba-
rium. Conidia, obtained in this way, may usually be kept for reference for an indefinite
period; and, since they allow the comparison of very large numbers of spores side by
side, are most convenient for study.

The artificial propagation of Empusae, by the infection of fresh hosts, I have found a
much more difficult matter than one would suppose, even when the host infected was of
the same species as that from which the spores were obtained for this purpose. Infec-
tion between dissimilar hosts I have found still more difficult; although, in two instances,
I have been successful in infecting caterpillars with H. Grylli developed on grass-
hoppers, as well as in transferring . sphaerosperma from leaf hoppers (Lyphlocyba)
to a Pieris larva. The method which I[ have adopted for infection consists in the use of
a tightly-covered jelly tumbler in which the upper portion is separated from the lower by
a round piece of wire netting. By placing the hosts to be infected in the lower of the
two chambers thus formed and fastening a specimen of H’mpusa in the upper one, the
living hosts below can hardly escape the spores discharged through the netting.

The period which ensues after the infection of a host until its death varies to some ex-
tent. In the larger hosts, such as flies or caterpillars, death may not take place for twelve
days; although the usual period is from five to eight days. In minute hosts this period
must be considerably shortened, owing to the ephemeral character of many forms known
to be subject to the attack of Empusae. The first visible symptom of the disease is a
general restlessness of the host. In caterpillars, for instance, the insect leaves its food
plant and wanders restlessly about; usually endeavoring to climb upwards before death,
which is apparently quite sudden and unaccompanied by contortions of the body. The
host insect thus remains clinging to the object on which it rests or is fastened to it by
rhizoids. Certain insects are fixed by the insertion of their probosces into the substratum
on which they rest, as is the case with aphides. The house-fly is, I believe, always fas-
tened by its proboscis which adheres firmly to the substratum. Where rhizoids are de-
veloped, they often appear before the death of the host, and I have seen a geometrid
moth, which was thus firmly attached to a pine needle, fluttering violently in its at-
tempts to escape.

In the account of the separate species of Empusae which follows I have used this
generic name for all the forms, employing the names Hntomophthora and Triplosporium
in brackets as groups of subgeneric value. In Hmpusa proper I have included forms
in which the branching of the conidiophores is of the simple type, and the formation of
resting spores presumably asexual, taking 7. Muscae as the type. Under Triplosporium,
J have included the two forms #. Fresenii and H#. lageniformis, the ‘position of which in
Empusa is only provisional. The group is characterized by the production of conidia
having a smoky tint, thick-walled, with evenly granular contents and producing peculiar
almond-shaped secondary conidia on capillary conidiophores; while its zygospores are
elliptical, each originating as a bud which rises upward from the point of conjugation
of gametes arising from two hyphal bodies. Further study of #. lageniformis may

ENTOMOPHTHOREAE OF THE UNITED STATES. 153

show that these characters, as regards the formation of resting spores, are not suffi-
ciently distinctive. Yet I doubt if this proves to be the case; and, should it prove
otherwise, I believe that the subgenus should be separated as a genus from other Hm-
pusae.

Under Lntomophthora, which I have used in brackets as a subgenus, I have included
all forms characterized by the production of typically digitate conidiophores; differing
from recent German writers in not considering this character of generic value, as well
as in omitting even as a subgenus the name Lamia given by Nowakowski to a single
form (2. Culicis).

In his extended paper on Entomophthoreae,! Nowakowski summarizes the generic
distinctions of Hmpusa, Hntomophthora and of his genus Lamia, as follows:

1. Eyromopuraora including ovispora, curvispora, conica, and Aphidis.

Fungus growth, one-celled or with filamentous branches.
Paraphyses, rhizoids and columella, present.
Conidiophores, branched.
Resting spores, zygospores (three species), azygospores (two species).
2. Lamia including the single form Culicis.
Fungus growth, filamentous.
Paraphyses, present.
Rhizoids and columella, absent (nie ma).
Conidiophores, unbranched.
Resting spores, azygospores (borne terminally).
3. Empusa including Grylli, Fresenii and Muscae.
Fungus growth, filamentous.
Paraphyses and rhizoids, absent.
Columella, present or absent. -
Conidiophores, simple.
Resting spores, azy gospores.

Whether Nowakowski in his text gives more satisfactory characters for the genus
Lamia than are shown in the above table I am unable to say; but, from the data here
given, the presence of paraphyses (which I have apparently overlooked in examining the
species) is the single point which separates it from Hmpusa as defined below it. The
opinion of Brefeld that the form should be separated as a connecting link between Hm-
pusa and Hntomophthora, based upon a tendency to a digitate type observable in the co-

__ nidiophores and upon the presence of rhizoids is more readily understood, yet singularly

4
|
;
'
i

enough, and erroneously I think, Nowakowski affirms the absence of both these points
of structure. In my own opinion, #7. Culicis cannot be separated from 2. Muscae by other
than specific distinctions; the points of similarity of the two being decidedly greater
than their points of difference. The same may be said of the two species subsequently
described as #. papillata and H. apiculata which bear somewhat the same relation to
HB. Grylli that 2. Culicis does to LH. Muscae; each having rhizoids and showing a slight
tendency, in the case of #. apiculata at least, to a digitate type of conidiophores.
Taking the genus Hntomophthora, as defined by Nowakowski in the same table, the
digitation of the conidiophores is apparently the only exclusive difference of importance
which separates it from Hmpusa. Even here . Culicis and E. apiculata tend to break
Tien neds. De 176.

154 ROLAND THAXTER ON THE

down the distinction, as already mentioned. No definite line can be drawn, also, as con-
cerns the production of resting spores; since in species of the sphaerosperma type, which
must be placed in Hntomophthora, we have exactly the same type of formation with that
oceurring in H. apiculata, which it is equally necessary to place in Hmpusa. It is true
that conjugation is not known in Hmpusa unless it is represented in the very question-
able type deseribed under #. Grylli; yet it is unsafe to assume that it does not exist, or
that its absence is of generic value. The only consistent way out of the dilemma con-
sists either in considering all the forms under the tolerably coherent genus Hmpusa, or
in resorting to further splitting to express transitional forms. The sphaerosperma section
of Hntomophthora, for example, shows decided differences from the rest of the group
in the character of its branching, in its conidia and secondary conidia as well as in its
formation of resting spores, and may, perhaps, with fuller knowledge of the species already
known or subsequently to be discovered, prove separable from the remaining forms.
Our knowledge of Empusae is at present in its infancy, and conclusions in respect to
subdivisions must be largely based on doubts; a foundation much more likely to pro-
duce confusion than a clear understanding of the group.

The use of the name Hmpusa in preference to “’ntomophthora needs a word of expla-
nation, since the two have, until comparatively recent years, been used in the same sense
to designate entomogenous Entomophthoreae generally. Although an Hmpusa had been
previously described by Fries under an erroneous generic name (Sporendonema), the
paper of Cohn! upon the “house-fly fungus” is the first in which the group was recog-
nized by a generic title, Hmpusa. This publication appeared in 1855, and in the follow-
ing year Fresenius, in an article’ preliminary to his more extended paper on the subject,”
pointed out that Hmpusa, having been preoccupied for a genus of orchids, should be
dropped, proposing Lntomophthora in its place. A few months later Lebert,’ taking the
same ground, proposed the name Myiophyton, over which the name of Fresenius of
course has priority. The two names have subsequently been used indiscriminately until
separated as two distinct genera by Brefeld and Nowakowski, who thus tacitly recog-
nized the validity of Hmpusa as a name; a validity also admitted by Cohn, Hidam,
Schroeter and DeBary who employ it without question. If therefore a single name is
to be used, Hmpusa certainly has priority and sufficient weight of authority to make its
use good. As a matter of fact the orchidaceous genus Hmpusa is placed as a synonym
in Bentham and Hooker’s Genera Plantarum, and seems unlikely to produce confusion
in any Case.

The position of the Entomophthoreae among the Zygomycetes is placed beyond a
doubt by the formation of the resting spores above described, yet it is interesting to note
that, until the publications of Nowakowski, and even subsequently, there has been much
difference of opinion concerning their true position; the weight of opinion assigning them
a place among the Oosporeae. The theory that the members of the group were merely
stages in the life-history of Saprolegniae, which has been maintained on a basis of actual
experiments as well as their supposed connection with the yeasts (Saccharomyces), is
manifestly incorrect and a matter of historical interest only. In the latter case it is of
interest to note that species of Saccharomyces very frequently occur in connection with

‘Lc. A. *l.c. B. PUT.

ENTOMOPHTHOREAE OF THE UNITED STATES. 155

Empusae in aphides and flies, the one class of hosts usually having a sweet secretion
and the other preferring sweet substances as food, thus supplying a nutritive medium
for the growth of yeasts in connection with the Hmpusa. It has occurred to me that the
frequent presence of yeasts in this connection might indicate a swectish secretion from
the Hmpusa itself in order to attract hosts for infection; but I have seen no indications
that this is the fact.

A natural arrangement of the species of Hmpusa is a matter of great difficulty,
since their characters do not, I think, indicate a single line of development. In the sue-
ceeding enumeration, for example, the two forms included under Triplosporium can
hardly be properly placed either at the beginning or at the end of the remaining series,
and their position between Hmpusa proper and Hntomophthora is equally unsatisfactory.
The near relations of the forms described as #. Caroliniana and EL. Lampyridarum is

also a matter of doubt which may perhaps be removed by further study. A list of the

remaining species found in Kurope and not yet distinguished in this country, with brief
characters and references, is appended for the convenience of students and includes, I be-
lieve, all published names not previously referred to. References given as J. c., 1. c. A,
etc., refer, as in the previous pages, to the appended list of papers consulted where full
titles and references are given.

EMpPusa Cohn, 1855.

Empusa Muscae Colin.
Pl. 14, figs. 1-9.

Empusa Muscae, Cohn l.c. A. Brefeld 1. c. A; l. c. B, p. 28; J.c.¢. Schroeter 7. ¢.,
p- 221. Nowakowski /. c. B, p. 176.
Entomophthora Muscae, Fresenius 1. ¢. A, p. 883; 1. c. B, p. 202, figs. 1-23. Giard Ll. ¢.,
p- 358. Sorokin J. c. C, p. 195, figs. 877, 582-585. Winter J. ¢.
Myiophyton Cohnii, Lebert 1. c.
?Sporendonema Muscae, Fries 1. c.
Conidia bell-shaped or nearly spherical, with a broad subtruncate base and sharply
pointed apex; 18 Xx 20,,—25 x 30,; containing usually a single large oil globule, and
surrounded after discharge by a mass of protoplasm. Conidiophores simple, broad

and stout, tapering gradually to a narrow base; emerging in white rings between the

segments of the host, without coalescing over its body. Secondary conidia like the
primary, or more commonly suboyoid, small, rounded at the apex and formed by direct
budding from the primary form. esting spores, azygospores, produced laterally or ter-
minally from hyphae within the host; spherical, colorless, 30-50, in diameter (Winter).
Host attached to substratum by proboscis.

Hosts. Diptera: Musca domestica, Lucilia Caesar, Calliphora vomitoria and other
large flies; also Syrphidae of several genera.

' Habitat. United States, Europe, South America.

This familiar Hmpusa is as common as it is widely distributed, and is at present the

_ only species known south of the equator. It is probable that it is as universal as its more

156 ROLAND THAXTER ON THE

usual host (Musca domestica) ; since, if not indigenous in remote localities, its transpor-
tation by sea would be almost inevitable. As a rule, the species is found about houses,
usually within them, occurring in great abundance from the latter part of June until late
in the autumn; yet its occurrence out-of-doors is an exceptional phenomenon and has
been noticed in only a few cases. This is the more singular, since hosts that are liable
to infection are very common in the open air, and a transmission to them of the dis-
ease from the house-fly would seem a very easy matter. Isolated examples of #. Muscae
are, however, almost never found in situations frequented, for instance, by Syrphus flies,
although Cornu! records an extensive epidemic in which the hosts attacked belonged
to this genus. In my own experience I know of only two instances of the isolated oc-
currence of this species out-of-doors. The first was observed early in July on Mt.
Washington where two small specimens of Syrphus were found on bushes in the alpine
region, both of which were infested by “. Muscae; and in the second instance a speci-
men of a small, yellow-bodied Syrphus was found at Albany in August on the flowers
of Solidago by Mr. A. F. Chatfield, and forwarded to me, the host in this case being at-
tacked by the same Hmpusa. Mr. Chatfield informs me that it was the only specimen
observed, and although I have searched with great care for similar specimens, I have
never seen a second instance of the kind. An epidemic in the open air, caused by #.
Muscae, I have, however, observed in one locality where a hairy black fly (Anthomyia sp.)
about as large as M. domestica, was found killed by this fungus. This locality was the
region in the immediate vicinity of the snow arch at the head of Tuckerman’s rayine,
on Mt. Washington, where the affected flies occurred sticking in large numbers to the
flowers of Solidago and Heracleum. These flowers were also visited by an abundance
of other flies, among them many examples of the same species of Syrphus previously
mentioned from Mt. Washington and Albany; but in no instance did I find one of these
or of the numerous other Syrphidae and Muscidae visiting the flowers, that showed
any signs of infection from the black flies with which they could hardly have failed to
come in contact. This failure of certain species to contract the disease, although known
to be subject to it, is interesting as indicating that even a slight change of hosts among
Empusae is often difficult, until the fungus has become established to some extent in its
new conditions, and may go far to explain the difficulty experienced in cross infection
subsequently mentioned under #. Grylli and H. sphaerosperma.
The species is readily distinguished by its pointed, bell-shaped spores which, although
entirely similar to those of #7. Culicis, are much larger. The probable rupture of the col-
umella has been previously alluded to (p. 144) and the surrounding pellicle of proto-

plasm gives a characteristic appearance to spores which, for example, have been discharged

upon a glass slide (figs. 5-6). One of the chief points of interest about the species is
the uncertainty that exists concerning its resting spores, which, although the form is so
universal have as yet been observed in only one instance. Winter? states that he discoy-

ered specimens of MM. domestica in-doors which contained resting spores, and also pro-

duced conidia which he identified as belonging to #. Muscae. It seems quite impossible

that Winter should have mistaken the conidia of any other species for those of #. Mus-

cae; yet this observation, although referred to, is not credited by Brefeld,who concludes
llc. B. 21. ¢.

———

ENTOMOPHTHOREAE OF THE UNITED STATES. 157

that the species never produces resting spores and is continued over winter in warmer
regions, whence it migrates northward with the flies on the return of summer. This
theory, however, does not coincide with my own experience of /’. Muscae in this coun-
try; since the first specimen which I observed at Cullowhee, where .M. domestica liter-
ally swarmed, was observed at about the same date at which it usually appears in the
north, namely July first. For three weeks previous to this date I saw no specimens at
Cullowhee; and although I have found not the smallest trace of resting spores in a sin-
gle instance, it seems improbable that the migration theory can apply to this country at
least.

Giard' also states that he found resting spores, which were produced externally, oc-
curring on specimens found in cool situations; but it is difficult to determine from his
description whether the bodies described are true resting spores, and the observation
needs confirmation. On plate 1, fig. 7 and plate tr, fig. 12, of Lebert’s paper,! this author
has also figured bodies that seem to be resting spores at an early stage of their formation.

The literature concerning H. Muscae is very voluminous; the first description of the
form having been given by DeGeer in 1782, according to Brefeld; and for further ref-
erences to this literature the elaborate papers of Cohn, Lebert and Brefeld above cited
should be consulted. Whether the first supposed description accompanied by a dis-
tinctive name, that of Fries,' really applies to the present species is, I think, extremely
doubtful; for the oil globules in #. Muscae could hardly have given rise to the expres-
sion “flocci fertiles erecti,.... intus sporidiis globosis referti,” whereas in species of the
ovispora type, this error of observation might readily have occurred.

Empusa Culicis A. Braun.
Pl. 14, figs. 10-16.

Empusa Culicis, A. Braun 1. c., p. 105.

Entomophthora Culicis, Fresenius J. ¢. B, figs. 44-45.

Lamia Culicis, Nowakowski l. c. B, p. 173, figs. 99-114.

Entomophthora rimosa, Sorokin (J. c. A, p. 146; 7. c. B, p. 393, Taf. xm, figs. 12-19
(with cut); J. ¢. C, p. 231, figs. 595-596, 575, 576, 603; 7. c. D, p. 58, plate 1, figs.
1-13. Nec H. rimosa, Schroeter U. ¢., p. 222.

_ ?Saprolegiha minor, Kitzing 1. c., p. 157.

Conidia bell-shaped or nearly spherical with a broad subtruncate base and sharply
pointed apex; 8 X 10,—15 X 16,, average 11.5 X 12,,; usually containing a single large
oil globule, and surrounded after discharge by a mass of protoplasm. Conidiophores
simple or with a tendency to become compound; broad at the apex and gradually taper-
ing to a narrow base; producing white or greenish masses which may or may not coa-
lesce over the body of the host. Cystidia present (Nowakowski). Secondary conidia
like the primary, or ovoid with rounded apex and formed by direct budding from the
primary spore. esting spores, azygospores, produced laterally or terminally from hy-
phae, spherical, colorless, 25, (? in diameter). Host attached by rhizoids.

ey ee

MEMOIRS BOSTON SOC. NAT. HIST., VOL TV. 23

158 ROLAND THAXTER ON THE

Hosts. Diptera: imagines of Culex and numerous genera of minute flies or gnats.
Habitat. Maine, New Hampshire, Massachusetts, Europe.

This is apparently the smallest of all the Empusae and is reported to be common in
various parts of Hurope. Although not previously accredited to this country, I have
found it repeatedly in the localities above mentioned. At Kittery, Maine, it occurred
early in July on very minute Diptera, adhering to the under side of the leaves of hop,
hollyhock and other plants growing about houses; and isolated specimens were found
in. similar positions in the neighboring woods, or marshy places. Although mosquitoes
(Culex) abounded in these localities, the only specimen of this insect that I haye seen
infested with #. Culicis was found on the edge of a small brook in the alpine region of
Mt. Washington. In this same locality, at the head of Tuckerman’s ravine, I have
found an insect also attacked by H. Culicis, whose reputation is perhaps worse even than
that of the mosquito, namely the “black fly” (Simulium molestum). ‘These specimens
were also found upon the under side of leaves, as in the case of the examples from Kit-
tery; although in Europe the more usual habitat seems to be such moist situations as are
afforded by the margins of brooks or the borders of tanks, in which, also, infected spec-
imens may often be found floating.

The form described by Sorokin as 1. rimosa seems certainly to belong to this species,
as has been pointed out by Nowakowski, although Sorokin, in his later publications, still
adheres to the opinion that his species is distinct. In describing #. rimosa,' Sorokin
states that the host is attached by rhizoids, and that the conidiophores appear on the
thorax, seldom on the abdomen of the hosts, producing bell-shaped conidia of which, so
far as I have seen, he gives no measurements in any of his publications. The resting

spores he describes as of irregular outline, produced laterally on internal hyphae, which ~

subsequently thicken, contract and, bursting the body of the insect, assume a vertical
position on the outside. He also remarks that, from the brief description of A. Braun,
it is difficult to say how far the two species (7. rimosa and EH. Culicis) are distinguished.
The figures of Fresenius from material received from Braun are, however, good, and
correspond to those of Sorokin in Cohn’s Beitrage.?

As regards the “stroma,” which Sorokin describes in this species, I have been unable
to satisfy myself; but where the fungus has developed with tolerable Juxuriance I have
found a condition very like that which he describes; namely, a mass of septate, anas-
tomosing, empty hyphae filling the body of the insect. In other cases, however, I have
observed the presence of spherical hyphal bodies or of chlamydospores (fig. 15), which ger-
minated and, after more or less branching, produced conidiophores in the usual way. The
resting spores are unknown to me, although I have frequently found small flies contain-
ing resting spores in company with the conidial form. In these cases the constant as-
sociation with specimens of /. sphaerosperma on similar hosts has made it impossible
to determine to which species the resting form belonged. According to the description of
Sorokin above quoted the resting spores would seem to be quite peculiar; yet Nowakow-
ski figures spores of the usual type borne terminally on long hyphae.

Were. C; ip. 231. 21. ¢c. B, Taf. xin, figs. 16-18.

eT

ENTOMOPHTHOREAE OF THE UNITED STATES. 159

Empusa Grylli (Fresenius).
Pl. 14, figs. 17-48.

Entomophthora Grylli, Fresenius 1. c. A; 1. c. B, p. 203, figs. 24-43. Sorokin 7. ¢. ¢, p.
211, fig. 653. Farlow, Ellis Exsiccati N. A. Fungi, No. 1401.
Empusa Grylli, Nowakowski J. c. B, p. 168, figs. 72-98. Schroeter J. ¢., p. 222.
Entomophthora aulicae, Reichhardt in lit. (see Bail Z. c.). Cohn J. ¢. B, p. 77. Sorokin
l.¢. C, p. 212. Schroeter 0. c., p. 221.
Entomophthora Calopteni, Bessey l. c.; Ellis Exsiccati, No. 1f01. oe
- Conidia ovoid to pear-shaped, with a broad papillate base and evenly rounded apex;
30-40), X 25-36, ; hyaline and containing one or more large fat globules. Conidiophores
simple, coalescing externally when growing luxuriantly, and arising directly from round-
ed irregular hyphal bodies, with or without subsequent branching. Cystidia wanting.
Secondary conidia of one kind, like the primary. esting spores spherical, colorless;
30-45, in diameter; produced terminally or laterally from hyphae, directly within or by
budding from hyphal bodies; or by a pseudo-conjugation between two divisions of a
single hyphal body. Host attached to substratum by the contraction of its legs.

Hosts. Lepidoptera: larvae of many genera of Arctians and of Orgyia nova. Orthop-
tera: larvae, pupae and imagines of many genera of Acridians. Imago of Ceuthophilus.
? Diptera: larvae and imagos of Tipulidae, ete. (see H. conglomerata).

Habitat. Maine, New Hampshire, Massachusetts, New York, Washington, D. C.,
North Carolina, Ohio, Iowa, Newfoundland, Europe.

As will be observed, by the synonymy given above, I have included under this species
the two forms described as H#. aulicae and H. Caloptent. The description of the first-
mentioned species by Cohn! is, I believe, the first mention of this name that is ac-
companied by any note which would render a determination possible. There can be no
doubt, I think, that the form common in this country on hairy caterpillars is the same
species described from Europe on similar hosts, since the American form agrees with the
European in all respects as far as can be ascertained from published data. Assuming
this identity, a comparison of the form on caterpillars and the still more common form
on grasshoppers, can hardly fail to afford convincing proof that the two represent a sin-
gle species, their general structure, development and appearance being the same, or
varying within similar limits.

I have observed numerous epidemics of the grasshopper form at Kittery in Maine,
near Boston and in North Carolina; and the caterpillar form seems also very common,
assuming, Mr. Howard informs me, an epidemic character among the Hyphantria larvae
which have recently done considerable damage to the shade trees in Washington.

In the summer of 1886, I found an epidemic early in September among grasshoppers
that were destroying the second crop in a field at Kittery,and also noticed a number of
Arctian larvae similarly affected in an adjacent garden. Being struck with the similar-
ity between the two, I endeavored to transfer the disease from the grasshoppers to cat-
erpillars, and for this purpose placed a larva of Spilosoma virginica and several of

Bl Cs5\ DP: 1Gs

160 “ROLAND THAXTER ON THE

Hyphantria teator in a jelly tumbler, and fastened above them a grasshopper from which
the spores were being rapidly discharged. ‘These larvae were then fed for eight days in
a closed jelly tumbler, at the end of which time the Spilosoma had died, and, soon after
being placed in a moist chamber, produced a luxuriant growth of conidiophores. In the
meantime all of the Hyphantria larvae had died from insect parasites, with the excep-
tion of two which spun cocoons after a few days. I was entirely unable to transfer the
disease from caterpillars to grasshoppers; but I was quite as unsuccessful in infecting
grasshoppers from grasshoppers. The reinfection of caterpillars I found more easy,
although about two-thirds of the -aterpillars used for this purpose showed no signs of
the disease and pupated as usual. I was unable to repeat the experiment of cross infec-
tion with any satisfactory result, owing to the fact that it was impossible to obtain cat-
erpillars in any number, or good material of /7. Grylli with which to infect them: I was
obliged therefore, in a second experiment, to use larvae of Pyrrharctia isabella which
were in the hibernating condition. Of five larvae used, one died in eight days and con-
tained resting spores; while the rest were not affected after several weeks. I do not
consider these experiments as in the smallest degree conclusive in themselves; but a
comparison of other species shows that the hosts of Empusae may be widely-different
in the same species, and therefore a specific distinction, which, as in the present instance,
would rest entirely on the character of the host, should not be considered of any value,
even if my experiments did not show that the hosts may be, to a certain extent, inter-
changeable.

I have been much surprised at the difficulty encountered in communicating the disease
among similar hosts, although in the case of grasshoppers this may be perhaps accounted
for from the fact that I used only imagines, which may afford a less ready entrance to
the germinating spores than younger stages of these insects. In the case of the hairy
caterpillars, however, I see no reason why infection should not have been successful in
every case. A specimen of Ceuthophilus, found at Kittery, which was discharging spores
in great quantities, was also used im an attempt to infect three individuals of the same spe-
cies which were confined with it in a small tin box. The living crickets were put into
the box late in the afternoon when the spore discharge was at its height, so that several
hundred spores at least must have come in contact with each specimen. On the follow-
ing morning the living crickets were not only well powdered with spores, but had eaten
about half of the infected specimen. Nevertheless, after having been kept for more
than two weeks, they showed no signs of the disease. In view of these facts, it is not
surprising that my success in cross infection should have been so incomplete, and it may
reasonably be assumed that so radical a change of hosts is probably a somewhat gradual
process even in nature, the fungus, as has been already noted, requiring one or more
generations to become firmly established under its new conditions of nutrition.

Since the species is so widely distributed and generally abundant, there seems to me
no good reason for believing that the resting spores described as 2. Calopteni and
found in Caloptenus at Ames, Iowa, belong to a different species; and I have therefore
placed this as asynonym. ‘Through the kindness of Professor Farlow, I have been ena-
bled to examine authentic specimens of 1. Calopteni collected by Professor Bessey which
differ in no respect from the usual resting spores of 1. Grylli. Professor Farlow has also

;
» ie

ENTOMOPHTHOREAE OF THE UNITED STATES. 161

allowed me to examine material of 1. Girylli received from Professor DeBary, and there
can be no question concerning the identity of the American and European forms. The
occurrence of the species in Newfoundland, where I found it on the larva of Orgyia nova
on the Salmonier river, should also be noted; since this is, I think, the most northern lo-
eality in America from which Empusae have been recorded.

Morphologically, the species is chiefly of interest from the pseudo-conjugation already
described on p. 149. I have not had an opportunity of studying the process by cultiva-
tions of hyphal bodies; and the figures which represent it (figs. 31-39) are drawn from
specimens which occurred simultaneously in a single grasshopper. ‘The process is not
uncommon, occurring chiefly in the femora; but in all cases the usual azygospores are by
far the most abundant form of resting spores. ‘The production of a double spore by the
incomplete union of the two halves of a hyphal body is not infrequent, resulting in forms
similar to that represented by fig. 47, in which the union was nearly complete. It sometimes
occurs also that there is no union between the two halves, and an azygospore is formed on
either side of the median partition. The most common mode by which azygospores are
formed is that represented in fig. 43, where the spore is the result of direct budding from
the usually irregular hyphal bodies. Ihave never seen in the caterpillar or in the grass-
hopper form a process of this kind which is wholly comparable with that figured under
H. conglomerata (figs. 60-61), for in this case the hyphal bodies are very regular,
nearly round, and bear the spores on a short neck. This process is, moreover, inyaria-
able in the Z%pula form as far as I have seen and shows none of the variations which
oceur in Girylli. The same process is figured by Nowakowski,' but it is not stated in
the explanation of the plates whether these figures are drawn from material on grass-
hoppers or gnats. The budding, from an arachnoid hyphal body, of spores, which in the
explanation of his plates’ Nowakowski calls “zygospores,” I have observed in only two
cases; but as there seems no indication in this of a sexual process, and Nowakowski in
his synoptical table of the species® places #. Grylli under “Azygospora,” I infer that
the use of “zygospory” in this connection is a printer’s error. A very common form,
which I have seen frequently in cultivations of hyphal bodies in water, is that repre-
sented in fig. 40, where the spore results from a terminal enlargement of the hypha of
germination. A formation from septate hyphae, as in fig. 45, I have seen only once or
twice; but the septation as well as the anastomosis and short projections associated with
it has, I think, no significance. The occurrence of resting spores is about equally com-
mon in caterpillars and in grasshoppers, and the association with them of conidia devel-
oped from the same specimen, frequently occurs. ‘The conidia as a rule show little
important variation in size or shape, the caterpillar form showing sometimes a tendency
to taper more gradually to a slightly broader base than in the grasshopper form; but, on
the other hand, I have never seen this tendency so marked in caterpillars as I found it in
the spores obtained from the Ceuthophilus above mentioned (figs. 25-26).

The earliest occurrence of this species that I have noticed was at Cullowhee, N.C.,
where I found a single specimen early in July. On the grassy summits of Roan Mt.,
N. C., it was epidemic in August and also in mowing fields at Cranberry, N.C. An
epidemic observed in September at Kittery has already been mentioned; and the latest

rie. B, fig. 94, 7 G2; p. 182: 6. B, polite

162 ROLAND THAXTER ON THE

occurrence that I have noticed was among caterpillars in Cambridge late in October.
The tendency of the affected hosts to crawl upwards before death, instead of concealing
themselves, as one would naturally expect, is noticeable in this, as in other Empusae,
and results ina far more effective dissemination of the spores. The Ceuthophilus above
mentioned, which usually lives under logs and in similar situations, had crawled up a bush
about six feet high and hung suspended from the topmost twigs; grasshoppers also almost
invariably crawl nearly to the top of the culms of grass before death, and are thus very
conspicuous and easily collected. Mr. Miyabe informs me that he has seen grasshoppers
in this position in Japan; but whether the Hmpusa by which they were attacked is H.
Grylli or not, I am unable to say.

For some mention of European epidemics caused by “Z. aulicae” which have been no-
ticed as far back as 1835, reference should be made to the papers of Cohn and Bail al-

ready cited.

Empusa Tenthredinis (Fresenius).
Pl. 15, figs. 49-55.

Entomophthora Tenthredinis, Fresenius 1. c. B, p. 205, figs.51-58. Sorokin J.¢. €, p. 212,
fig. 652.

Conidia broadly ovoid, tapering slightly towards the apex and with a prominent, rather
narrow papillate base; 25 X 35,—35 X 55,4 (62.5, = maximum length, sec. Fresenius).
Conidiophores simple, coalescing over host. Secondary conidia like the primary. eest-
ing spores unknown. Host attached to substratum by its legs. Rhizoids not observed.

Hosts. Hymenoptera: larvae of Tenthredinidae.

Habitat. Kittery, Maine; Europe.

T have referred to this species a form found early in September upon a small Tenthredo
larva feeding upon Scutellaria in a swampy situation among woods. The larva when
found was hanging flaccid by its prolegs, and the conidiophores were just beginning to
emerge in small tufts over its body. The spores are somewhat smaller than those de-
scribed by Fresenius, nor is their difference from H. G‘rylli as decided as represented in
Fresenius’ plate. A slight tendency to taper more equally from the middle of the spore
towards the base and apex, as well as its usnally more delicate papilla, may separate it
from Grylli to which it is closely allied. It is apparentlyrarely met with even in Europe,
the only mention that I have seen beyond that of Fresenius being a reference by Cornu?
toan Hmpusa on Tenthredo larvae. The reference and figure in Sorokin’ are taken from
Fresenius.

Empusa conglomerata (Sorokin) ?.
Pl. 15, figs. 56-62.
Entomophthora conglomerata, Sorokin l. ¢c. A; l. c. B, p. 388, Taf. xm, figs. 1-11; JU. ¢.
C, p. 228, figs. 574, 594, 592.
? Hmpusa Grylli, Nowakowski (in part) J. c. B, p. 168.

Aide (C2 Aspe So. Tce

> ee et

ENTOMOPHTHOREAE OF THE UNITED STATES. 163

Oonidia broadly ovoid, usually with a single large oil globule; 22 x 25,—25 x 40,;
average 23 X 32,. Conidiophores, simple. Secondary conidia, like the primary. testing
spores, azygospores, produced from spherical hyphal bodies and borne on a neck-like
process of variable length. ost floating on water, or among moss in water.

Hosts. Diptera: larvae and imagines of 'Tipulae.

Habitat. Mt. Washington, N. H.; Cullowhee, N. C.; Europe (on Culex).

It is with great hesitation that I have referred to this species a form found in the small
brooks which arise in the locality known as the Alpine Garden on Mt. Washington and
also very rarely at Cullowhee. In the former locality, the Zipula larvae were very fre-
quently met with among moss over which water was running. These larvae were dead
having a milky color, and after being placed upon slightly damp moss which absorbed
the excess of moisture from them, produced conidia with great rapidity; but in not very
considerable quantities. On examination, the body was found in every case to be filled
with resting spores in various stages of development, and the conidiophores were present
in such small numbers that a “stroma,” such as is described by Sorokin in this species,
would not have been apparent. The conidia closely resemble those of #. Grylli, and
usually contain a single large oil globule in the centre. The difference in habitat be-
tween #. Grylli and the present form is certainly very great, and it is doubtful if Z.
Grylli would survive soaking in running water for a week or more as is necessarily the
case with the 7%pula larvae above mentioned. The regular production of resting spores
from nearly spherical hyphal bodies is not such as is found in #. Grylli and this is the
only morphological difference that I have been able to find between the two. Whether
material in good condition and free from resting spores would show the “ stroma” of So-
rokin, remains to be determined; but judging from the spores figured by this.author,! as
well as by the host and habitat, the present form at least approaches very nearly to Z#.
conglomerata. Sorokin gives no measurements of the conidia that I have been able to
find, but shonld the measurements correspond, the conidia of the two forms would be in-
distinguishable. Sorokin states that the conidium is discharged together with a body of
protoplasm from the basidium, a circumstance which, in the examination of dried material,
I have not been able to verify in the present instance.

In the plates of Nowakowski' certain of the figures of #. Grylli are drawn from ma-
terial on Culex, and this author is inclined to think that Z. Grylli and 2. conglomerata
are the same. The figures referred to do not wholly corroborate this view and it may be
mentioned that one among them’ exhibits the same regular formation of resting spores
from spherical hyphal bodies that I have represented in figs. 60 and 61.

Empusa apiculata, nov. sp.
Pl. 15, figs. 63-70, 74-75.
Conidia nearly spherical, with a prominent papillate base, terminating in a short,
sharp and abrupt point; 28-30, X 30-37, average 30 X 35,. Conidiophores simple, some-
times with a tendency to become digitate, originating directly or indirectly from nearly

Pirie. 1. 21. c. B, Plate xr, fig. 94.

164 ROLAND THAXTER ON THE

spherical hyphal bodies. Secondary conidia like the primary. esting spores, azygo-
spores or zygospores(?), formed laterally or terminally from hyphae, spherical; hyaline,
30-45,. Host attached to substratum by long and conspicuous rhizoids, few in number
and terminating in an irregular, disc-like expansion.

Hosts. Lepidoptera: larva of Hyphantria textor, imagines of Tortrix sp., Deltoid sp.,
Petrophora sp. (geometrid). Diptera: numerous genera of small flies or gnats. He-
miptera: imago of a species of leaf hopper (Z'yphlocyba).

Habitat. Maine and North Carolina.

Var. major.
Pl. 15, figs. 71-73.
Conidia more nearly spherical; 38 X 45,,—55 X 60,; basal papilla smaller in propor-
tion to the body of the conidium than in the typical form.
Host, Coleoptera: imago of Péilodactyla serricollis ( fide Henshaw).
Habitat. Cullowhee, North Carolina.

It is with some reluctance that I have given a new name to this form, although by the
presence of strong rhizoids and by its apiculate papilla it seems a well-marked species.
The existence of three allied species, #. Jassi, H. Planchoniana and LE. conglomerata,
concerning neither of which is any information procurable beyond the insufficient data
already published, makes the description of a related form necessarily dangerous, so that
the present name is in a measure provisional until more complete descriptions or figures
of the three forms mentioned are published. The case is rendered still more confusing
by the occurrence on aphides of the species described below and placed provisionally un-
der #. Planchoniana. 'This may prove to be the same with the form under consideration,
and both may be identical with #7. Planchoniana; yet, what the latter species is, it is
wholly impossible to determine from published data.

In the present species we have the first recorded instance of an Hmpusa growing up-
on a lepidopterous imago as its host, although, as will be subsequently seen, this is not an
unique case. ‘The geometrid moth, above mentioned as one of its hosts, was taken on
the wing, flying slowly with an unnatural fluttering motion and being placed in a col-
lecting box it was soon fastened to a leaf by five or six long and powerful rhizoids.
These on examination were found to be made up of several hyphae each ending in an
irregular expansion (fig. 75) around which a hyaline substance seemed to have been se-
creted, converting it into a disc-like sucker. Where several of these terminations had
touched the leaf at adjacent points the several expansions usually coalesced to form one
large “sucker,” with a continuous even outline formed by the secretion just mentioned.
This moth contained both conidia and resting spores, the latter forming in a manner ex-
actly resembling that subsequently mentioned under H. sphaerosperma. The appear-
ance of a resting spore haying its origin in connection with a cross partition, as in fig.
74, occurred occasionally and seemed wholly analogous to the similar appearance in Z.
sphaerosperma (figs. 214-216).

The conidiophores, in many instances, arise directly from nearly spherical or elliptical
hyphal bodies (fig. 64); but in some cases I have observed a condition where the body

7 i

ENTOMOPHTHOREAE OF THE UNITED STATES. 165

has been filled with a coherent mass of empty, interlacing hyphae resembling the
“stroma” described by Sorokin and previously referred to. The conidiophores, which
are clear white, coalesce over the body to a great extent, forming an envelope of consid-
erable thickness. They sometimes tend to become digitate, so that this species, together
with #. Culicis, forms a connecting link between the simple and compound types.

The species occurs not uncommonly in North Carolina on the under side of leaves
in Lehododendron thickets; and I have found it occasionally in Maine near brooks or
marshy places in woods, always on leaves. The specimen on Hyphantria textor (larva)
was found at Burbank, E. Tenn., in one of the nests peculiar to these caterpillars; but,
although there were many in the nest, I found no additional specimens attacked by the
fungus. The cmnivorous character of the species is noticeable, and experiments with
infections of different hosts are much to be desired, especially with aphides, since it is
only by this means that the true relations between this and the succeeding form can be
determined.

Empusa Planchoniana (Cornu) ?.
Pl. 15, figs. 76-78.

Entomophthora Planchoniana, Cornu 1. c. A, pp. 189, 190; 7. c. B, foot-note, p. 4. Sor-
okin J. c. C, p. 214.

Conidia nearly spherical or broadly ovoid, with a papillate base which is sometimes
furnished with a short sharp point. Average measurements 28-33, < 30-40,. Conid-
tophores simple, partially coalescing over the host. Secondary conidia like the primary.
Resting spores, azygospores, produced laterally or terminally, more commonly intersti-
tially, from hyphae; spherical, or very irregular in the interstitial forms ; 35-50, in diameter.
Host attached to substratum by the insertion of its proboscis.

Hosts, Hemiptera: several genera of aphides.

Habitat. Kittery, Maine; vicinity of Boston, Mass.; Europe.

It is with much hesitation that I have placed under the above name a species occurring
in this country commonly, yet never very abundantly, on numerous aphides infesting the
white birch, Bidens and other plants, in late summer and autumn, associated as a rule
with other species which attack the same hosts. It is sometimes found also associated
with #. Aphidis in greenhouses where it may be found during the winter months. It
is very nearly related to HL. apiculata, and, if not a variety of this species, forms a con-
necting link between it and #. Grylli. It differs from H. apiculata chiefly in the ab-
sence of rhizoids, which I have been unable to discover in fresh material after a careful
search, as well as by the variability ofits conidia which are rarely pointed as in /. apicu-
lata, and vary from a form nearly spherical to one not separable from that of even the
longer forms of H. Grylli. The species may be placed under '. Planchoniana only pro-
visionally as may be understood from the following descriptions of the last named spe-
cies by Cornu.

In speaking of the species,’ Cornu says that the conidiophores, issuing from the body

Loe INE

MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 24

166 ROLAND THAXTER ON THE

of the aphides, “donnérent naissance a une sphérule mucronée, remplie d’un plasma ré-
fringent et au centre de laquelle apparaisait une spore en forme de toupie d’Allemagne.
Dans lair humide les sporanges furent lancés au loin,” etc.: and in the only other place
where I find the species characterized,’ he says “Cette espece parait characterisée par la
production . . . de spores ovoides oblongues, sans sporanges, ou sporanges soudés a la
spore” (the italics his). I am unable to reconcile these two descriptions or to determine
whether the author here realizes what I consider to be the true morphology of the m-
pusa conidium. ‘The phenomenon of the separation of the outer wall I have never seen
in the round spored species of the “Gvylli” type to which the present form belongs, and
such a separation so exceptional in any case, that its occurrence as a characteristic of the
general morphology of any species is highly improbable. A “sphérule mucronée” may
refer to a conidium of the “Muscae” type; yet since the conidia are characterized as in
the form“ de toupie d’Allemagne” as well as “ ovoides oblongues” this seems doubtful.
The last expression perhaps refers to another species on aphides (the common #. Aphi-
dis) ; yet any opinion concerning the form to which L. Planchoniana belongs is purely
conjectural, since the above quotations which furnish all the published data concerning
the species are not of such a nature as to render its determination possible.

Empusa papillata nov. sp.
Pl. 15, figs. 82-90.

Conidia broad-ovoid, evenly rounded, with a very large tongue-like slightly truneate
papilla, clearly defined from the spore body. Average measurements 35 x 50,, maxi-
mum 50 x 75,. Conidiophores stout, simple. Secondary conidia like the primary. Rest-
ing spores azygospores (?), 45-55, in diameter, spherical, slightly brownish. Host at-
tached to substratum by a few large rhizoids, terminating in a Se expansion.

Hosts. Diptera: several minute gnats.
Habitat. Mt. Washington, N. H.; Cullowhee, N.C.

I first noticed this species on the wet Sphagnum surrounding a spring in the locality
known as the Alpine Garden on Mt. Washington, where it occurred in July and August
(1886). I also found a small number of specimens on very minute gnats in the beds of
mountain brooks at Cullowhee, in company with several other species, which occurred on
moist logs and in similar situations. The conidia sometimes attain a size greater than
any other H’mpusa known to me and are peculiar for their prominent tongue-like papil-
late base. They are formed usually in small numbers and are visible to the naked eye
without difficulty. Like 2. apiculata, this form is peculiar for its few powerful rhizoids
which attach the host firmly to the moss or other substratum on which it rests. It differs
from the last-mentioned species in its much larger conidia which are of a more ovoid
shape, while it apparently lacks entirely the sharp point peculiar to the basal papilla of
EE. apiculata. It is not impossible that the form on Culex referred by Nowakowski to
HE. Grylli may be the present species; yet, as previously mentioned, I am inclined to think
that he refers to the species I have called EZ. conglomerata. The two forms, #. conglom-
erata as above described and the present species, are, I think, quite distinct.

1. cB.

ENTOMOPHTHOREAE OF THE UNITED STATES. 167

The resting spores of this species occurred in several specimens simultaneously with
conidia, but were in every case too far advanced in their development to demonstrate
their process of formation, which can hardly vary greatly from that of the nearly allied

EE. apiculata.

Empusa Caroliniana nov. sp.
Pl. 16, figs. 91-105.

Conidia ovoid, oblong or long elliptical, with rounded extremities, the base hardly sep-
arable from the apex; without large oil globules; measuring 10 x 26,-—15 x 45y, average
14x 37,. Conidiophores simple, barely projecting beyond the body of the host between
the body segments and from the thorax; originating directly from rounded hyphal bod-
ies. Secondary conidia like the primary. esting spores (azygospores) spherical,
hyaline, 37-55, in diameter, average 45, (?). Host attached to substratum by its legs.

Hosts. Diptera: imagines of Tvpula sp.

Habitat. North Carolina.

This species is decidedly different from any form known to me and is easily recognized
by its shapeless conidia which, although they are of the H’ntomophthora rather than H’m-
pusa type, are borne on conidiophores which are rarely branched within the body of the
host and are perfectly simple at their extremities; the hyphae swelling directly to a ba-
sidium upon emerging. Specimens producing the fungus with the greatest luxuriance may
therefore show little indication of its presence, and in dried material it is almost wholly
invisible, the body segments closing over the basidia in shrinking. <A single specimen
only was taken at Cullowhee, while at Cranberry I procured a considerable amount of
excellent material. The affected insects (a brown Zipula with mottled brown wings)
were found in a small group of hemlocks among deciduous woods and occurred invaria-
bly hanging from the lower dead twigs, about which the extremities of their long legs
were knotted in such a manner that it was impossible to disengage them. Several spec-
imens contained only hyphal bodies and I was thus enabled to see the greatest possible
development of conidiophores, by placing the Zipulae in a moist atmosphere. Other
specimens produced both conidia and resting spores, although I was unable to make out
the origin of the latter. As far as could be judged from the examination of material
in which the process was already completed, it consisted in a budding from rounded hy-
phal bodies, but no satisfactory observation was possible in any case. The terminal and
interstitial production of hyphal bodies (fig. 92) through the successive contraction of
the contents of branching hyphae was frequently observed; but in other cases rounded
hyphal bodies occurred, associated with resting spores, which were much larger than
those represented in the figure and may have had a different origin.

Empusa (Triplosporium) Fresenii Nowakowski.
Pl. 16, figs. 106-140.
Empusa Fresenti, Nowakowski l. c. B, p. 171, Pl. xu, figs. 115-125. Schroeter J. ¢.,
p. 222.

168 ROLAND THAXTER ON THE

Conidia nearly spherical to short-oyoid, often with a short, truncate or commonly
slightly papillate base; with granular contents; without large fat globules, and slightly
smoky in color; 15 x 18,-18 x 20,. Conidiophores simple, arising directly from small,
spherical hyphal bodies of a yellowish color. Cystidia not observed. Secondary co-
nidia of two kinds: the first like the primary, the second almond-shaped and borne
obliquely on capillary conidiophores. esting spores, zygospores, elliptical or subovoid,
yellowish, becoming often smoky and opaque, formed by the conjugation of two small,
spherical hyphal bodies by means of slender gametes, above the point of junction of
which the spore rises as a bud; average measurements 30 X19,. Host attached to sub-
stratum by the insertion of its proboscis.

Hosts. Hemiptera: Aphis mali and very many other aphides.

Habitat. Maine, Massachusetts, North Carolina, Europe.

The name adopted above for this interesting species is that used by Nowakowski in
his Krakow paper’, although, to avoid confusion, it should be mentioned that the same
author in his review of this publication’ uses the name “/’resentana” by an apparent
oversight. The species is a very common one, having been found by Nowakowski on
numerous aphides and also recorded by Schroeter as belonging to the Silesian flora.
Although it has not been previously noticed in America, I have found it very common
at Kittery, Maine, in the vicinity of Cambridge and also as far south as Cullowhee, N. C.,
where both the conidial and zygosporic forms occurred on an Aphis infesting Solidago.
At Kittery, a black Aphis on poppy, as well as the common apple Aphis, was found at-
tacked by #. Fresentt about the middle of June; and the last mentioned host contained
abundant zygospores even at this early date. Ihave found the same species on aph-
ides infesting Bidens and other plants about Cambridge as late in the season as the first
week of October; but here no resting spores occurred. The formation of the resting
spores, illustrated by the series of figures (127-140), has already been described in
some detail (p. 148). As far as can be determined from alcoholic or dried material, the
masses of protoplasm (figs. 106-108) from which the conjugating hyphal bodies are de-
rived, have no proper wall, a circumstance which has been previously noted by Sorokin
in connection with his 2. colorata. Before reproduction commences, these protoplasmic
masses become divided, rolling themselves into small, spherical hyphal bodies (fig. 127 ),
which, when developing, certainly show the presence of a surrounding wall. This wall,
during the process of conjugation, becomes considerably thickened, so that the two hy-
phal bodies remain attached to the spore in the form of bladder-like appendages which
are tolerably persistent (figs. 135-138). The zygospores, which have been hitherto un-
known, differ from all other described forms by their elliptical shape. In very mature
specimens, they are sometimes almost black and opaque, though I am unable to say
whether this is due to the absorption of coloring matter from the host; or whether, as
seems more probable, the resting spores may not assume a smoky color, analogous to
that of the conidia, which is deepened by age.

The conidia are readily distinguished by their small size and smoky tint, as well as
by the peculiar almond-shaped secondary conidia of the second type, borne on slender,

Ui Canese ? Bot. Zeitung, XL, p. 561.

ENTOMOPHTHOREAE OF THE UNITED STATES. 169

thread-like conidiophores, which may be seen produced from them abundantly in any
preparation, the ordinary form of secondary conidia being of rare occurrence. The pri-
mary conidia possess more than usually refractive, homogeneous contents, in which are
embedded numerous fine granules; and the thickness of the spore wall is noticeable as
in the succeeding species, although in the present instance it is not indicated in figs. 110
-116. The growth of the fungus is never luxuriant, and each spherical hyphal body,
from its small size, can hardly give rise to more than one or two conidia.

As already mentioned, I have taken this and the succeeding species (1. lageniformis)
as the types of a new sub-genus, Triplosporium, which will, I think, prove to have a
generic value when further information has been obtained concerning the development
of the last-named species.

Empusa (Triplosporium) lageniformis nov. sp.
Pl. 16, figs. 141-160.

Conidia slightly smoky, flask-shaped, with a truncate, hardly papillate base, rounded
apex and evenly granular contents; average measurements 20 x 35,, maximum 30 X 38,.
Conidiophores simple, or when young sometimes fasciculate or pseudodigitate ; terminat-
ing by a weak, tapering basidium. Cystidia not observed. Secondary conidia like the
primary, or almond-shaped and borne obliquely on capillary conidiophores. esting
spores unknown. Host attached to substratum by the insertion of its proboscis.

Hosts. Wemiptera: usually aphides on Betula populifolia.

Habitat. Maine, Massachusetts, North Carolina.

The discovery of the resting spores of this species is perhaps the most interesting fact
that remains to be observed among American Empusae, owing to its undoubted affinity
with H. Fresenii. The species being of larger dimensions than 7’. F’resenii, we may
look for an instance of true conjugation which may be even more readily followed than
in the last mentioned form. I have found only scattered examples of this species in sin-
gle localities, although it is generally distributed in company with LZ. occidentalis, sub-
sequently described. Both forms occur, as far as Ihave observed them in New England,
only upon a large Aphis generally found in abundance on the white birch in August
and September. Numerous specimens examined contain no signs of resting spores, pro-
ducing only conidia which are similar to those of H. Presenii, except as regards their
larger size and somewhat peculiar shape. The single specimen collected at Cullowhee
occurred on an Aphis infesting Solidago, so that it is probable that the disease could be
readily propagated among greenhouse aphides, for example, and thus afford a means of
observing its further development.

Empusa (Entomophthora) Lampyridarum nov. sp.
Pl. 17, figs. 161-172.

Conidia regular, ovoid; slightly tapering towards the apex; with an abrupt, broad,
slightly papillate base; contents granular, without large oil globules. Measurements

170 ROLAND THAXTER ON THE

14 x 30,-20 x 37), average 15 x 35». Conidiophores digitate (?). Secondary conidia
like the primary or more commonly long-cylindrical, rounded at either end, and borne ver-
tically on capillary conidiophores. Resting spores unknown. Host attached to leaves,
etc., by its mandibles.

Hosts. Coleoptera: imago of Chauliognathus Pensylvanicus.

Habitat. Cullowhee, N. C.

This interesting species was unfortunately not observed by me until a day or so before
leaving Cullowhee, so that my material is limited to two specimens in fair condition, yet
not sufficiently good to determine definitely the character of the conidiophores which, I
have little doubt, are typically digitate. The specimens were allowed to discharge their
conidia in a damp chamber so that the conidiophores were apparently exhausted by the
operation; and those remaining were of the character represented in fig. 161. The sec-
ondary conidia of the second type are very peculiar, and separate the species at once from
all others by their vertical position upon the conidiophore, as well as by their peculiar
shape which is exactly that of a watermelon.

In the absence of more definite knowledge concerning the structure of the conidio-
phores, as well as from the lack of material containing resting spores, the affinities of the
species are somewhat doubtful. It seems allied both to Zriplosporium and to the sphae-
rosperma group of Hntomophthora; but the type of development in its resting spores
must be observed before this can be determined.

The melon-shaped secondary conidia are produced in great abundance, even in a fairly
moist atmosphere, and in only one or two instances I observed a second form like the
primary conidium in process of formation. In many cases, the more common secondary
conidia were larger than the spores from which they were produced, and this, together
with the apparent thinness of the spore wall, seems to indicate that they are not as re-
sistent as is usually the case with secondary conidia when borne on capillary conidio-
phores. It will also be noticed that the secondary conidiophores are much less thread-
like than is usually the case.

The affected beetles (fig. 172) were found firmly attached by their mandibles to grass
or leaves in open fields; and, to judge from the number of heads that I observed in this
position from which the bodies had been broken away, I should infer that the species
had been not uncommon in the locality mentioned. The same beetle was abundant at
Burbank, E. Tennessee, yet here I observed no specimens of the Hntomophthora.

Empusa (Entomophthora) geometralis nov. sp.
Pl. 17, figs. 173-178.

Conidia short-elliptical to ovoid; 15-22» x 10-12,; contents finely granular, with a
hyaline nuclear body. Conidiophores digitate, coalescing. Cystidia not observed. Sec-
ondary conidia like the primary, or long almond-shaped and borne obliquely on capillary
conidiophores. vesting spores borne laterally or terminally on short hyphae as in #.
sphaerosperma; spherical, colorless, average diameter 30,, maximum, 35). Host attached
to substratum by numerous rhizoids issuing from the abdomen at nearly the same point,
and for the most part coalescing.

a A.

te re,

ENTOMOPHTHOREAE OF THE UNITED STATES. 171

Hosts. Lepidoptera: imagines of geometrid moths (Petrophora, Hupithecia, Thera,
etc.).
Habitat. Kittery, Maine.

This species was found during the month of September (1886) attacking geometrid
moths of several species in or near pine woods, a favorite habitat of these insects. It is
usually the habit of the host to rest with the abdomen curved upwards and, at one point
of the under surface, resting on whatever object the moth may have lighted upon, usu-
ally apineneedle. At this point of contact, and, as far as I have observed, nowhere else,
the rhizoids are produced in a tuft which thus fastens the insect by its abdomen. The
rhizoids appear before death and I have found a small Hupithecia fluttering violently in
its efforts to free itself from a pine needle to which the rhizoids had already become firmly
attached (fig. 173). Although the specimens collected were found for the most part on
the borders of pine (P. strobus) woods, several were noticed in other situations, as for in-
stance, in a room used by me for collecting night moths by means of a lamp. Here sey-
eral specimens of Hupithecia, thus attracted, were found fastened to the walls and win-
dow panes. The species was not studied while fresh and none of the dried specimens
were in the proper condition for showing clearly the method by which the resting spores
are formed. As far as could be seen, however, the process is similar to that described
in 1. sphaerosperma.

The conidia are peculiar and may be at once recognized by their short, thick form,
which readily distinguishes them from those of the closely allied EL. sphaerosperma.

Empusa (Entomophthora) occidentalis nov. sp.
Pl. 17, figs. 179-199.

Conidia of the sphaerosperma type, sometimes slightly fusiform, often tapering strong-
ly towards the apex, with a broad, rounded, papillate base. Average measurements
35 X 102, maximum 45 x 12,. Contents usually finely granular, sometimes with larger
fatty bodies. Conidiophores irregularly digitate, coalescing in a white or slightly yel-
lowish mass. Cystidia slender, slightly tapering. Secondary conidia like the primary,
or long almond-shaped and borne obliquely on capillary conidiophores. esting spores,
azygospores or zygospores (?), borne laterally or terminally by budding from the hyphae;

- colorless, spherical, 20-35, in diameter. Host attached to substratum by numerous

rhizoids.
Hosts. Hemiptera: aphides on Betula populifolia.
Habitat. Maine, Massachusetts.

This is a well marked species of the sphaerosperma type, and eccurs very commonly
on the aphides which usually infest the common white birch in late August and in Sep-
tember. It generally is associated with the much rarer . lageniformis which attacks
the same host, and it may be found, in my experience, in almost any locality where the
white birch grows. The conidia are chiefly noticeable from such forms as are repre-
sented by figs. 183 and 184 which strike the eye at once in examining a preparation.

_ The contents of the conidia are usually finely granular with a central nuclear body (figs.

172 ROLAND THAXTER ON THE

185-189) ; but sometimes contain fatty globules of considerable size. The resting spores
often occur in specimens also producing conidia, and are commonly formed by lateral
budding from short hyphae in an apparently non-sexual fashion; but numerous in-
stances occur, as in 7. sphaerosperma, where the budding is associated with a partition,
as in figs. 196, 198-199, which may perhaps indicate a sexual process. - In a few cases
spores developing from long hyphae growing in the legs seemed to result from a process
which may with safety, I think, be considered a form of conjugation (fig. 197).

The species has little that is peculiar in its structure and is only interesting as being
another example of the strongly marked sphaerosperma type.

Empusa (Entomophthora) sphaerosperma (Fres.).
Pl. 17, figs. 200-219.

Entomophthora sphaerosperma, Fresenius 1. c. A, p. 883; 1. ¢. B, p. 207, Taf. rx, figs. 68—
78. Sorokin J. c. ¢, p. 220, figs. 579-81, 586-90, 632-33, 654. Schroeter JU. c., p. 223.

Tarichium sphaerospermum, Cohn 1. c. B, p. 84.

Empusa radicans, Brefeld l. c. A; 1. c. B, p. 14, Taf. 1-11.

Entomophthora radicans, Brefeld l. c. C;/.c. D. Nowakowski J. c. A; l. ¢. B, p. 165,
Taf. x, figs. 63-67, Taf. x1, fig. 71.

Entomophthora Phytonomi, Arthur l. c. A; l. c. B.

Conidia long-elliptical to nearly cylindrical; papillate at base and tapering very slightly
near the rounded apex; 15-26, x 5-8,, average 20 x 5.5,; usually with a fine granular
contents and a central oval nuclear body. Conidiophores much branched and confluent
over the body of the host, forming usually a mass the upper surface of which is flattened.
Conidiophores digitate. Color of the fungus as a whole white, varying to bright pea
green. Cystidia slender, tapering, not abundant. Secondary conidia like the primary,
or long almond-shaped and borne on a capillary conidiophore. esting spores, azygo-
spores or zygospores (?), borne laterally or terminally from hyphae; 20-35,, average
25,3 spherical, hyaline or very slightly yellowish. Host attached to substratum by rhi-
zoids.

Hosts. Lepidoptera: imago of Colias philodice; larva of Pieris. Hymenoptera: Ich-
neumonidae of several genera and species, a small bee (near Halictus). Diptera: imago
of Musca domestica (Brefeld), Musca sp. (Roan Mt., Thaxter) ; numerous small species
belonging to the Culicidae, Mycetophilidae, Tipulidae and other families. Coleoptera: lar-
va of Phytonomus punctatus; imago of one of the Lampyridae. Hemiptera: Aphis sp.;
several species of T’yphlocyba (leaf hoppers), larvae, pupae and imagines. Neuroptera:
imago of Limnophilus (?) (Schneider). Thripidae: larvae, pupae and imagines of a
species of Thrips on Solidago.

Habitat. Maine, New Hampshire, Massachusetts, New York, North Carolina, EKu- :
rope.

It is unnecessary to remark that this species is peculiar for the great diversity of its
hosts which include all insect orders, excepting only the Orthoptera. It is an extremely
common form, probably from this reason, and often produces epidemics of considerable

ENTOMOPHTHOREAE OF THE UNITED STATES. 173

proportions. It was first reported from this country by Mr. J. C. Arthur who describes
it as Hntomophthora Phytonomi n.s., having found it destroying the clover weevil ( Phy-
tonomus punctatus) in great numbers in the vicinity of Geneva, N. Y. The affected
larvae, just before death, crawl up blades of grass, ete., and curling themselves around
them near the summit are attached by the rhizoids in this position. Material of the
Phytonomus form received by me from Professor Riley, which was collected, I believe,
by Professor Lintner at Albany, N. Y., shows no sufficient differences which can sepa-
rate it from the same form on other hosts, although the average measurements of the
conidia are very slightly larger than in the majority of cases, the maximum length given
by Arthur being 28,, while as a rule I have seldom found it more than 25,. The shape
of the spores is identical with that which characterizes the other forms and is similar to
the published figures of 1. sphaerosperma to which all the forms occurring on the hosts
above enumerated should, I feel confident, be referred.

In my own experience, I have observed two epidemics caused by this species: one
among certain small flies in a wood near marshy ground at Kittery, Me., where the
hosts occurred in considerable numbers fixed by the fungus on the under side of the
lower leaves, a few feet from the ground. The second instance occurred in two orchards
in the same locality where the hundreds of the previously mentioned epidemic were re-
placed by tens of thousands, the host in this instance being the leaf-hopper ( Z'yphlocyba
mali and rosae), a pest only too well known to cultivators of roses. Having first ob-
served it in some abundance on roses in a garden, I was led to make an examination of
adjacent apple orchards, and found the lower branches of the trees literally covered with
the affected hosts, a dozen or more being often fastened to a single leaf. Unfortunately,
I was too late, and in almost all cases the specimens had discharged their spores, while
no more hosts remained for infection. A few, however, were still producing conidia,
and it occurred to me to endeavor to infect from them the larvae of Pieris, which is the
common European host of this species. For this purpose I placed a small number of
young larvae in the bottom of a jelly tumbler, fixing the infected hosts above them as
previously described. This was on Sept. 10 (1886); on Sept. 16, the majority had pre-
pared to pupate, the larvae having been too far advanced when infected. One larva, how-
ever, on the evening of the sixteenth, was found dead and attached to the leaf on which
it had been feeding by powerful rhizoids which issued from the region of the prolegs.
This larva was not disturbed for twenty-four hours, in the hope that conidiophores might
make their appearance, but none appeared, and the insect became slightly collapsed.
Upon examination, it was found to contain numerous, spherical resting spores, about 25,
in diameter, the origin of which could not be seen, all traces of hyphae having disap-
peared owing to a partial decomposition of the contents of the caterpillar which also
contained several larvae of Pteromalus. This fact surprised me greatly, since, in his
infection experiments, Brefeld states that no result was produced when spores were sown

on larvae thus infested. A double parasitism was also found in my experiments with
EH. Grylli previously mentioned, in which the larvae of certain insect parasites issued
from several caterpillars thickly covered by conidiophores. The remaining larvae in the
present experiment died with Pteromalus or pupated within a day or so. Several died
from Pleromalus after pupation, and the remainder, three or four in number, died before

MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 25

174 ROLAND THAXTER ON THE

or after pupation and were found to contain irregular bodies resembling hyphal bodies,
but often without apparent walls and associated with a general fatty degeneration of the
whole contents of the pupa. At this date (Sept. 17) it was only possible to procure very
poor material for infecting a fresh set of Pieris larvae, and although much younger larvae
were selected than in the previous experiment, no results were obtained; the caterpillars
upon reaching maturity either dying from insect parasites or pupating.

Although these experiments by themselves are not by any means convincing, the in-
fection of even a single Pers larva from a host so totally different, and under circum-
stances such as Ihave described, when taken in connection with the structural similarity
existing between the American and European forms, furnishes im my opinion sufficient
ground for considering them as belonging to a single species.

The occurrence of this species on a butterfly (Colias philodice), fig. 200, is also an in-
teresting fact; the specimen in question, which was found on the ground in a pasture
at Kittery, being, I believe, the first recorded instance of this nature. This is also 1
think, the only species that has been found to attack hymenopterous imagos, on which
it very commonly occurs; a fact that might be of interest to bee-raisers, should the fun-
gus develop a local fondness for bees. In this connection it may be noted, however, that
several hives of bees placed under the trees in the apple orchards above mentioned,
showed no signs of any entomophthorous disease.

The species probably has a very wide geographical range, and although in North Caro-
lina [have found it less common than in New England, it occurred in some quantities on a
fly, somewhat smaller than Musca domestica, which I found fixed to the under sides of the
leaves in Rhododendron thickets on the summit of Roan Mountain. On Mt. Washington,
N.H., [have found it infesting flies, ichneumons, and a minute Zhrips which it destroyed
in great numbers. This occurrence upon Thrips is interesting as illustrating the omniyo-
rous character of the parasite. Krasilstchik, in his list of insect hosts attacked by fungi,
gives Thrips as the host of an undetermined species of Hntomophthora which is, I believe,
the only other recorded instance of this insect as an H/mpusa host. The infested larvae, —
pupae and imagines of this insect, as they occurred on Mt. Washington, were hardly vis-
ible without a hand lens. Both conidia and resting spores occurred in this instance; the
former somewhat smaller and more irregular than in the case of hosts whose size admits
of a more luxuriant growth of hyphae, yet differing but little from the usual type.

The general appearance of the fungus in this, as well as in the succeeding species,
when it is well developed on its smaller hosts, is almost always sufficiently peculiar to
distinguish it from other Empusae. 'The whole mass of conidiophores coalesces over the
body often leaving only the middle of the thorax uncovered; but instead of presenting
the rounded form usualin other Empusae, the upper surface has a flattened appearance,
and is the only portion from which conidia are discharged. This is due to an oblique
tendency observable in the growth of the main hyphae, as is indicated in fig. 202, the left
hand portion in the figure corresponding to the outer part of the whole mass. The ba-
sidia thus have a general tendency to poimt upwards instead of in all directions as is
usually the case. The occurrence of specimens in which the mass of conidiophores is
colored green or greenish is not common, and the color fades on drying; but in two
cases in the epidemic among leaf hoppers just mentioned, I found specimens in which it

ENTOMOPHTHOREAE OF THE UNITED STATES. 175

was colored a vivid pea green, a circumstance that can hardly be due to any coloring
matter from the host, which is of a pale yellowish tint. A similar coloring will be noticed
presently under . dipterigena.

The formation of the resting spores in this species has already been mentioned (p. 147).
The instances figured (figs. 214-217) were taken from two leaf hoppers, the only speci-
mens that I have examined in which the development of the spores was at exactly the
proper point for observing their origin. The differences apparent between this process
and that figured by Brefeld' are, in my opinion, merely the result of the difference ex-
isting between the conditions present in either case; the totally dissimilar nature of the
host being in itself a sufficient explanation. It should be noticed also that in the legs of
these same specimens the hyphae were long and continuous, and, although no resting
spores had begun to develop in them, an occasional anastomosis was apparent; while the
same is true of the preceding species (7. occidentalis) in which resting spores were ob-
served in a similar situation in connection with hyphae which showed anastomoses here
and there.

Empusa (Entomophthora) Aphidis Hoffinan.
Pl. 18, figs. 220-240.

Entomophthora Aphidis, Hoffman in Fresenius /. c. B, p. 208, figs. 59-67. Winter
l.c. Sorokin J. c. C, p. 213, figs. 595-594, 6354; J. c. Dp, p. 60, plate u, figs. 14-18.
Nowakowski /. c. B, p. 164, figs. 59-62.

Tarichium Aphidis, Cohn 1. c. B, p. 84.

Entomophthora ferruginea, Phillips /. ¢., p. 4, plate 11, figs. 1-13.

Conidia ovoid to elliptical or subfusiform; commonly asymmetrical and very varia-
ble; with papillate base and containing numerous oil globules. Average measurements
25 X 12,,, maximum 16 x 40). Conidiophores digitate, often simple. Hyphal bodies spher-
ical, germinating in all directions and giving rise to numerous contorted hyphae which
grow into conidiophores. Cystidia rather slender and tapering at their extremities.
Secondary conidia like the primary, or short ovoid with a single large oil globule. est-
ing spores “spherical, 33-45, in diameter and borne terminally or laterally on hyphae”
(Fresenius and Sorokin). Host attached to substratum by rhizoids, few in number, and
usually terminating in a disc-like expansion.

Hosts. Wemiptera: Aphides of numerous genera.

Habitat. Maine, New Hampshire, Massachusetts, N. Carolina, Washington, D. C.,

Europe.

It is of course impossible to determine whether the description of Fresenius’ really
refers to this species or to other forms found upon aphides and producing similar rest-
ing spores; yet there can be no doubt that the conidia first described by Winter? and
subsequently described and figured by Nowakowski are identical with those of the form
above described. Although I have not myself observed the resting spores of this spe-
cies, they are described by Winter and Sorokin as spherical, so that the assumption is
justified that in the present instance we are dealing with the true 2. Aphidis, which must

ie GED 21. ¢..B. 6

176 ROLAND THAXTER ON TUE

otherwise be distributed among at least four other species having spherical resting spores
and growing upon aphides, namely, 4. sphaerosperma, [. occidentalis, H. Planchoniana
and the form under consideration. I have, it will be noticed, placed 2. ferruginea as a
synonym of this species, although Mr. Phillips states that his species, in the opinion of
Mr. Cook, is a distinct form, as shown by a comparison with authentic specimens of 7.
Aphidis. The figures and descriptions of /. ferruginea, however, as far as I can judge,
point to the present species; and moreover the exsiccati specimens of H. Aphidis are
unreliable, the two numbers that I have examined containing in the one instance nothing
whatever, and in the other #. Hresenti, a species which cannot be confounded in any
way with #. Aphidis on account of its peculiar resting spores.

Although this species (#7. Aphidis) has not, to my knowledge, been previously reported
from the United States it is, with the exception of #. Muscae and perhaps #. Grylli, the
commonest of all the Empusae; occurring abundantly in the localities above mentioned.
It was first called to my notice by Dr. George Dimmock who noticed it in a greenhouse
in Cambridge during the winter of 1886. in this situation it acted as a decided check
to the multiplication of the aphides, yet did not spread with sufficient rapidity to render
“smoking” in the greenhouse unnecessary. At Kittery I have found it on numerous
genera of aphides and especially destructive to the forms which injure the hop. In one
case I observed a large hop vine some twenty feet high completely covered with aphides
which were killed off by this fungus in about two weeks; the affected hosts being fas-
tened to the under sides of the leaves, and to the younger shoots in vast numbers. The
destruction of colonies of Aphis by this species or by #7. Fresenii seems to be the rule
rather than the exception, and is at least of very common occurrence. An instance of
the kind was called to my attention during the second week in June of the past year
(1887) by Mr. L. O. Howard, who showed me great quantities of aphides dying of the
disease on clover near the agricultural department buildings in Washington. The prob-
able agency of ants in spreading these epidemics is worthy of notice as well as that of
night moths, especially Noctuidae, which, as well as ants, are often attracted in great
numbers by the sweet secretion of the aphides.

Despite the abundance of the conidial form, I have never obtained a single specimen
of the resting spores that I have been able to discover among my material. The conidial
form is chiefly of interest from the peculiar “germination” of the hyphal bodies repre-
sented in fig. 239, and consisting in the production, from a central cell with a highly re-
fractive contents, of a mass of hyphae growing from it in all directions, and subsequently
giving rise to the conidiophores. ‘This at least is the usual derivation of the mass of
contorted and branched hyphae which may be found filling the aphides just before the
external appearance of the conidiophores. The number of these cells or hyphal bodies is —
small, as may be inferred from the enormous number of hyphae which each produces,
and their origin is a question which I have been unable to settle from actual observa-
tion; although in a few cases I have found large hyphae at a less advanced stage of the
development of the fungus, the contents of which were collected terminally or intersti-
tially into rounded masses which may have represented the hyphal bodies in question.

The conidia are noticeable from their considerable range of variation, both in size and

Myc. Univ. No. 1916; Herb. Myc. No. 768.

ENTOMOPHTHOREAE OF THE UNITED STATES. Wea

shape. The conidiophores are white in the mass, often tinged with yellowish or flesh
color from the coloring matter of the host, which usually assumes a pale brick-red tint at
or just before death. This change of color is, however, common to most aphides attacked
by Empusae and cannot be considered distinctive of any species. In one instance I have
found a form, apparently this species, on a large bug (one of the Corisiae?) ; but, unless
the species subsequently described as /. dipterigena proves to be the same fungus, there
is little variation from the usual host.

Empusa (Entomophthora) dipterigena nov. sp.
Pl. 18, figs. 241-250.

Oonidia variable in shape, ovoid to oblong or subfusiform, with a papillate base, often
bent to one side, and containing numerous large oil globules; average measurements
11X22., maximum 15X30,. Conidiophores digitate coalescing over the body of the host
in a clear white, very rarely bright pea green mass. Cystidia slender, tapering toward
the apex. Secondary conidia like the primary or broad-oyoid. Resting spores (zygo-
spores?) produced externally in grape-like clusters ; spherical, hyaline, 20-40, in diameter.
Host attached to substratum by rhizoids; few in number, large, with a disc-like terminal
expansion.

Hosts. Diptera: small Tipulae; other small flies or gnats belonging especially to the
Mycetophilidae.

Habitat. Maine, New Hampshire, Massachusetts, North Carolina.

Before discovering specimens of this species producing both the conidia and resting
spores simultaneously, I was inclined to regard it as a mere variety of H. Aphidis; but
the peculiar external production of the resting spores, taken with its generally smaller
measurements and quite different host, serves sufficiently to distinguish it. It is nearly
allied to H. ovispora and L. echinospora, but separable at once from the first by its slender
tapering cystidia, and from the second by its smooth resting spores. From EF. Ameri-
cana it is separable by its smaller, often subfusiform conidia, as well as by the presence
of cystidia, its general habit and peculiar rhizoids.

' None of the specimens found contained resting spores at a sufficiently early stage of
their development to show the nature of their origin. The youngest examples, in which
the spore contents were still granular, indicated a tendency to produce distinctly grape-
like clusters, and in all cases the spores were external. The species is not uncommon,
occurring only on the under side of leaves in woods or thickets, and was first noticed
on Mt. Washington in late August, at the head of Tuckerman’s ravine, and subsequently
collected in swamps about Kittery, Maine, in small numbers. In North Carolina, it was
more common in similar situations, both forms of spores occurring not infrequently.

I have placed the #. rimosa of Schroeter! as a doubtful synonym of this form, with
which his description coincides with little variation. Schroeter’s species is certainly not
the #. rimosa of Sorokin, the spores of which belong to a very different type.

UL. ¢;

178 ROLAND THAXTER ON THE

Empusa (Entomophthora) virescens nov. sp.
Pl. 18, figs. 251-261.

Conidia ovoid to oblong, of irregular shape; with bluntly rounded base and apex, the
former often hardly papillate and not well distinguished from the apex; color greenish yel-
low in dried material; containing numerous small, irregular, often rod-like fat bodies;
measurements 10x 20,-16X36,, average 14X30,. © Conidiophores digitate, arising indi-
rectly from spherical hyphal bodies which germinate in all directions, giving rise to very
numerous hyphae which subsequently become conidiophores. Cystidia not observed.
Secondary conidia like the primary. Nesting spores unknown. Host attached to sub-
stratum by rhizoids?

Hosts. Lepidoptera: larvae of Agrotis fennica.

Habitat. Ottawa, Ontario (Mr. Fletcher).

The specimens from which the above description was taken were received by Professor
Farlow from Mr. J. Fletcher, Dominion entomologist, who writes concerning them as
follows:—‘“In the spring of 1884 from May 15 until the end of the first week in June,
all the gardens and fields in the district around Ottawa were severely attacked by the
larvae of Agrotis fennica. The disease of which you have a specimen was first observed
about the 22nd of May, and was extremely virulent. Dead larvae were to be found in
all directions; on stone walls, on fences and particularly on the tops of stems of grasses.
They were also vigorously assailed by Tachinidae and Carabidae. The Hntomophthora,
however, was undoubtedly the influence which brought this insect down again to its
normal rare occurrence at Ottawa.” The specimens received were black and shrivelled,
the fungus appearing as a greenish yellow coating, emerging in small tufts, which, in the
more mature specimens, appear to have coalesced over the body. The conidia appear
also greenish yellow in the mass, and are recognized by their general shapelessness and
rounded extremities, as well as by the numerous small fatty bodies of a crystalline ap-
pearance which characterize the spore contents. I have placed this species near #. Aphi-
dis from the structural similarity indicated by the peculiar germination of the hyphal
bodies already described in the last-named form; but the conidia seem to be of a different
type.

It should be noted that the host of this species is closely allied to that of #. mega-
sperma of Cohn which also occurs upon an Agrotis larva. Mr. Fletcher writes me that
he has not observed a single specimen of the fungus since the date above mentioned, and
as the material originally sent contained only conidia I am unable to give any information
concerning the resting spores. The conidia of #. megasperma are unknown, nor has the
species been observed to my knowledge since it was described by Cohn? The resting
spores of 7. megasperma are fortunately an exception to the general rule, being readily
recognized by their dark brown, reticulate epispore, so that the question concerning the
identity of the present form with Cohn’s species can be settled beyond a doubt as soon as
the resting spores of the one or the conidia of the other become known.

Die ep 183

ENTOMOPHTHOREAE OF THE UNITED STATES. 179

Empusa (Entomophthora) Americana nov. sp.
Pl. 18, figs. 262-273.

OConidia long-ovoid, with a broad evenly rounded apex; tapering for some distance to
a papillate base often slightly bent to one side. Within the spore are usually numerous
fatty bodies often very regular in size and shape. Average measurements 28-30, x 14,,
maximum 35 x 15. Conidiophores regularly digitate, arising from large, irregular, round-
ish hyphal bodies, and coalescing over the host in a mat-like covering which becomes
slightly rust colored on exposure. Cystidia absent. Secondary conidia like the primary.
Resting spores, colorless, hyaline, spherical; average diameter 38-45,, maximum 50,.
Process of formation not satisfactorily observed. Host attached to substratum by num-
erous filamentous rhizoids, without terminal root-like expansions; forming an even mat-
like attachment continuous around the abdomen of the host.

Hosts. Diptera: Musca domestica, M. vomitoria, Lucilia Caesar, and numerous other
large flies.

Habitat. New England and North Carolina.

This common species is frequently met with from June to October on the borders of
woods, near brooks or in shrubbery about houses. The host is generally found fixed to
the under, rarely on the upper, side of leaves or on bare twigs, a few feet from the
ground. It can readily be distinguished by its general habit from any species known to
me with the exception of 1. echinospora; since the rhizoids instead of growing out in the
form of numerous scattered threads are developed in an even layer around the hosts’
body forming, with the conidiophores, a continuous mat-like covering which becomes
often dark rust colored on exposure to the weather. The mass of conidiophores is at
first pure white, and in a moist chamber grows with great luxuriance.

The conidia are almost identical in appearance with those figured by Nowakowski as
belonging to ZH. ovispora and the measurements are very nearly the same. /. ovispora
is, however, at once separated from the present species by its peculiar cystidia which re-
semble those belonging to H#. sepulchralis (fig. 306). In the present species, I believe
there are no cystidia whatever, and I have looked in vain for anything remotely resem-
bling them. Whether the type of conjugation found by Nowakowski in L. ovispora
exists also in the present species, I am unable to say, since in all cases in which I have
found resting spores, the latter were mature and no trace of their method of produc-
tion was visible. H. Americana is also closely allied to #. muscivora of Schroeter which
seems to be identical with 2. Calliphorae of Giard. The resting spores in both these in-
stances are described as chestnut or deep chestnut brown; and since the material of both
seems to have been abundant, I have no hesitation in separating them from our species
in which the spores are always perfectly hyaline. They occur not infrequently in con-
nection with the conidia, and my material is sufficiently large to demonstrate the invaria-
bility of their color or lack of color. In North Carolina the species was of rarer occur-
rence than in New England, and I obtained but few specimens on shrubs in open woods
or on twigs of hemlock. It has been taken also by Professor Farlow and Mr. Miyabe at
Woods Holl, Mass., and a specimen from New Hampshire which I have not examined

180 ROLAND THAXTER ON THE

microscopically is in Dr. Hagen’s collection of entomogenous fungi. I have collected it
frequently at Kittery and in the vicinity of Boston, and it has been sent to me from Jaffrey,

NE.

Empusa (Entomophthora) montana nov. sp.
Pl. 18, figs. 274-288

or

Conidia, ovoid to turbinate, usually tapering from a broadly rounded apex to a some-
what attenuated, slightly pointed base, containing numerous large oil globules and meas-
uring 11 X 18,-15 x 25,. Conidiophores digitate, coalescing over the host in a livid
white mass and arising directly from rounded hyphal bodies. Cystidia tapering or rounded
at the apex, larger than the conidiophores. Secondary conidia like the primary or short
ovoid. esting spores unknown. Host attached to substratum by numerous rhizoids.

Hosts. Diptera: a minute gnat, apparently Chironomus sp.

Hatitat. Alpine summit of Mt. Washington, N. H.

This small species was found late in August, 1886, in great abundance on a small gnat
common about one of the brooks running into the “Lake of the Clouds ” on Mt. Wash-
ington; several hundreds of specimens being obtained from the wet Sphagnum bordering”
the brook. I have observed it in no other locality, even on Mt. Washington, although
thorough search was made in similar localities in other parts of the mountain. The species
presents no peculiarities of interest beyond the shape and size of its conidia which are
readily distinguished by their usually pointed base and broad apex which give them the
appearance of a long top. |

Empusa (Entomophthora) echinospora nov. sp.
Pl. 19, figs. 286-305.

Conidia ovoid, tapering to a papillate base ; usually nearly symmetrical ; 20-25 x 10-14, ;
containing one or more large oil globules. Conidiophores digitate, coalescing into a mat-
like covering which turns rust colored on exposure. Cystidia not observed. Secondary
conidia like the primary or varying only slightly. esting spores, zygospores, spherical
3040, in diameter, the exospore spinose; commonly produced externally as well as in-
ternally, and in the former case held slightly, after maturity, by a delicate mesh of hy-
phae. Host attached to substratum by rhizoids, coalescent around the abdomen in the
conidial form.

Host. Diptera: imago of Sapromyza longipennis and rarely other smaller Diptera.

Habitat. Maine, New Hampshire, North Carolina.

A single specimen of this interesting species containing both resting spores and conidia,
together with several examples that were useless from exposure, were found in August,
1886, among the alders at the head of Tuckerman’s ravine, Mt. Washington, on the pretty
yellow-winged fly that appears to be its almost invariable host. The conidia so nearly
resembled those of #. Americana and LH. dipterigena that it was only by accident that
I examined the specimen a second time after having placed it with my material of these

ENTOMOPHTHOREAE OF THE UNITED STATES. 181

species. Having discovered the peculiarity of its resting spores, I looked for it with some
care in North Carolina during the succeeding summer and was rewarded by finding the
same host repeatedly infested by the same fungus. In Carolina it occurred almost in-
variably on the under side of leaves especially of Jmpatiens growing beside brooks in
the woods. The conidial form was extremely rare, but of the resting condition [ pro-
cured some dozens of specimens. In very many cases the resting spores are produced
wholly, or more commonly partially, outside the body of the host, having originated from
hyphae (fig. 297) which emerge after the manner of conidiophores, and subsequently con-
jugate as shown in figures 298-302. Certain of these hyphae are seen to project some
distance beyond the rest (fig. 297) and ultimately form a delicate web which serves to
hold the mass of spores to some extent. None of my material was sufficiently good
clearly to show conjugation within the body of the host, and the hyphae were so evan-
escent and filled with such large globules of fat that points of conjugation could hardly
be made out in the confused mass. The spines develop more rapidly within the body
than without and as a result of their formation the abdomen becomes greatly inflated.
This inflated appearance together with the peculiarity of the host are sufficient to dis-
tinguish the species in collecting, and it is a singular fact that this particular species of
fly (Sapromyza), even in situations where 1. dipterigena was common and /. Americana
not infrequent, never appeared to be attacked by any other Hmpusa. 'The spinose char-
acter of the spore is due to elevations of the rather thin-walled epispore only, and is thus
readily obliterated by long exposure or transformed into a roughness of the surface.
The epispore may also be easily removed by pressure of the cover-glass upon it, disclos-
ing within a spherical resting spore of the usual type. The species is very nearly allied
to H. dipterigena, the conidia of the two being hardly separable in some cases. The pa-
pilla is, as a rule, broader in /. echinospora and the spores seldom tend to become fusi-
form. The type also represented in figures 243-244, which is characteristic of groups
of conidia in the former species, is wholly wanting in the latter as far as I have observed.

Empusa (Entomophthora) sepulchralis nov. sp.
Pl. 19, figs. 306-326.

Conidia long-ovoid to long-elliptical or subfusiform, rounded at the apex and with a
-papillate base commonly bent to one side; hyaline, with numerous large oil globules;
measurements 35-48 x 10-15, maximum 15 x 55). Conidiophores digitate, arising from
large (60, diam.) spherical hyphal bodies and coalescing over the body of the host in a
clear white mass. Cystidia very large (70-90, in diameter), slightly expanded or com-
monly becoming branched at their apices. Secondary conidia like the primary or short-
ovoid. esting spores, zygospores, spherical, hyaline, 35-50, in diameter ; formed as the
result of a Spirogyra-like conjugation between two hyphae and arising by budding from
the gametes. Host attached to substratum by numerous rhizoids.
Hosts. Diptera: imagines of Tipulidae.
Habitat. North Carolina, E. Tennessee.

This fine species was collected at Cullowhee, Cranberry and Burbank from June 20
MEMOIRS BOSTON SOC. NAT. HIST., VOL IV. 26

182 ROLAND THAXTER ON THE

to Sept. 5 of the past summer (1887), occurring commonly on the largest Tipulae, which
were often found in considerable numbers adhering to wet logs or similar objects along
the small brooks, so constantly met with in the Carolina mountains. Localities most at-
tractive to the Tipulidae were naturally the most productive of the Hntomophthora and,
in situations where the brooks were obstructed by fallen trees or roots over which they
partially flowed, a dozen or more often occurred side by side. A plentiful supply of
moisture seems always necessary for the development of the fangus, which is only found
on surfaces saturated with water. This circumstance results in a very luxuriant growth
of the conidiophores which makes this species the most conspicuous of any form on Dip-
tera known to me. Although the abdomen of the host is usually narrow and not more
than a few mm. broad, the conidiophores, after bursting through the integument about
the thorax and between the segments, become confluent and spread to some distance on
either side of the body forming a clear white mass of considerable dimensions. The ef-
fect thus produced is decidedly ghost-like, especially when a number of Tipulidae are
seen in this condition beneath a shaded log, and has suggested the specific name.

The species is remarkable from its formation of true zygospores in a fashion similar
to that discovered by Nowakowski in his /. ovispora, 2. conica and L. curvispora. I
was unable to determine that the zygospores were formed from the same hyphae which
bear the conidia, as stated by Nowakowski in the species above mentioned, and it seems
more probable from my observations that certain of the hyphal bodies develop conjugat-
ing hyphae, while others develop conidiophores. I was unable to satisfy myself on this
point, since cultivation of the chlamydospores in water produced only conidia; and, in
specimens producing zygospores, the hyphae were invariably too much broken up to
allow of any definite conclusion in this respect. I found no instances in which zygo-
spores alone were formed and usually the number was comparatively small. They were,
however, almost invariably present in greater or less abundance in the considerable num-
ber of specimens examined; yet only in a small number of cases did I find them in the
early stages of formation. This is apparently due to the great rapidity of the process
after it has once begun, since, in several instances, specimens in which no zygosporic
formation was visible when first examined, contained perfectly formed zygospores after
the lapse of a few hours. The singularly large cystidia are very noticeable and readily
seen with the naked eye, the drop of moisture which, as a rule, they bear at their apices
giving them the appearance of conidiophores with single apical spores of unprecedented
dimensions. The species is allied to Z. ovispora and LE. conica as well as EZ. rhizospora
with all of which it agrees exactly in the origin of its zygospores. It is perhaps most
nearly allied to H. ovispora from which, however, it differs by its much larger and dif-
ferently shaped conidia, which although subject to some variation in size and shape, es-
pecially when developed in situations where the supply of moisture is insufficient, are
yet tolerably constant at from 40 to 50, in length. The ease with which the outer wall
becomes separated in this species is noticeable in fresh material, and in several instances
I observed this phenomenon carried to such an extent that the spore proper floated free
within the inflated and spherical mother cell (fig. 321).

It should be noted that the occurrence of this species although common was decidedly

local, and in no instance did I find it in company with allied forms at even a short dis-
tance from the water.

ENTOMOPHTHOREAE OF THE UNITED STATES, 183

Empusa (Entomophthora) variabilis nov. sp.
Pl. 20, figs. 327-343.

Oonidia usually varying according to the period of their discharge, those first formed
being ovoid, short and stout, with a papillate base and broadly rounded apex and meas-
uring about 15 x11,. Those formed later are much more elongate, either shaped like
a short straight club or strongly curved, and measure 18-30 x 7-9,, average 25 X8,,
Conidiophores digitate, having in the mass as a rule a distinctly olive tint. Cystidia in
small numbers, slightly tapering, larger than the conidiophores. Secondary conidia like
the primary, of two general types. esting spores unknown. Host attached to sub-
stratum by numerous rhizoids.

Hosts. Diptera: minute gnats of various genera.

Habitat. North Carolina.

I have found this small species pretty generally associated with H. conica in Carolina
especially at Cullowhee, where it occurred not uncommonly in the beds of wood-brooks
and was found by turning over stones or wet pieces of wood in these situations. It sel-
dom occurs, in any abundance in one locality, and is very difficult to find from the min-
ute size of the insects which it attacks: yet it is almost always recognizable by the olive
color of the conidiophores which, though not invariable, usually affords a ready means of
separating it from other species with which it may be associated. I know no other spe-
cies in which a peculiarity in the tint of the conidiophores as a mass serves as a dis-
tinguishing character, although the occurrence of a bright green specimen has been
noted in /¥. sphacrosperma and E. dipterigena. In these cases, however, the colored
forms are rare exceptions. The variation of the primary conidia from short-ovoid (fig.
343) to straight or curved forms several times longer than broad (figs. 329-342) is a
noticeable feature in this species, and led me at first to separate my material into two
sets which I considered distinct species. By allowing the discharge of spores to con-
tinue for a longer time I have, however, repeatedly seen the longer form replace the
shorter one, and I think there can be no doubt of their specific identity. The secondary
conidia of the second type are nowise different from these first formed primary conidia.

The resting spores, I feel confident, I found in one instance; the insect containing them
being associated with others bearing conidia. The specimen, which has unfortunately
been lost, had produced no conidia so that I was unable to verify this opinion. From
memory I can only say that the spores were small in size, decidedly brownish and held
together by the hyphae from which they were formed. These hyphae, as in the nearly
allied #. rhizospora, seemed somewhat indurated: but they were formed internally, and
did not produce the rhizoid-like outgrowths which characterize the last named _ species.
The resemblance of this form to #. curvispora should be noted, many of the spores close-
ly resembling those figured by Nowakowski as belonging to this species.

Empusa (Entomophthora) rhizospora nov. sp.
Pl. 20, figs. 347-348.
Conidia, in form, like a straight short club, varying to almost crescent-shaped; very
variable, tapering more or less at either extremity, the basal portion of the spore neck-like

184 ROLAND THAXTER ON THE

and bearing the rounded papilla of attachment; contents with large fat globules; average
measurements 30-35 x 8-10,, maximum length 42,. Conidiophores digitate, coalescing
in a livid white mass over the insect. Cystidia large, not numerous, slightly tapering.
Secondary conidia like the primary, or spherical with an abrupt, delicate papillate base.
Resting spores, zygospores, spherical, 40-60”, with brownish epispore; budding from
Spirogyra-like gametes and subsequently Rrounded by rhizoid-like outgrowths which
are closely applied to the spore and originate at its base. ‘The hyphae producing zyg-
ospores are always external and subsequently become thickened and horny, turning
dark chocolate brown and holding the spores in a spongy mass. Host attached to sub-
stratum by numerous rhizoids.

Hosts. Neuroptera: several genera of Phryganeidae (imagines).

Habitat. Kittery, Maine; and North Carolina.

This interesting form was first observed by me at Kittery, where I found one or two
specimens producing only resting spores, under boards or logs in swampy situations.
From the peculiarities of its spores and their external formation, I was inclined at first
to consider it as the type of a different genus; since none of these specimens were in
sufficiently good condition to demonstrate the method by which the spores were formed
and the hyphae had already become brown and indurated. In North Carolina, I found
both the conidial and the zygosporic form very common, both kinds of spores often ap-
pearing on the same specimen. The affected hosts were not, as in the preceding species
with which it is commonly associated, exposed in open sight; but, in accordance with the
hiding habit of the caddis flies (Phryganeidae), were found concealed under saturated logs
or very commonly under stones, partially exposed in the bed of shallow wood streams,
or in swampy places in woods. ‘The larvae were also common in the same situations,
but I never observed that they were attacked by the fungus.

Although a very large number of specimens were examined I only found a very few
in which the process of conjugation was visible, and even in two instances where it had
not begun at sundown, I found it completed during the forenoon of the following day so
that its details could not be seen. ‘The process is thus, as in the preceding species, a
very rapid one. The persistence of the hyphae, concerned in the formation of zygospores
and their subsequent modification, is very peculiar as compared with the evanescent
character of the hyphae which distinguishes the family in general. The utility of the
modification, together with that of the rhizoid-like outgrowths which hold the spore, is
quite apparent in this particular case; for, owing to the peculiar habits of the host, the
fungus is developed in situations such as those described, in which it is liable to be flooded
and washed away at any moment when the water of the brook rises even an inch or so.
The thick elastic hyphae, under such circumstances, hold the mass of spores with great
tenacity, and the whole is fastened to the substratum by the indurated rhizoids with such
firmness that a knife is required to scrape it off. It is probable that the whole collection
of zygospores, having hibernated thus, germinate in the spring, growing out into a coa-
lescent mass of conidiophores as in the ordinary asexual type (fig. 377) ; but, although I
found specimens that, from their appearance, must have been in the brooks for several
months, no spores were observed that showed signs of germination.

The growth of the conidiophores is very luxuriant, greatly exceeding the size of the

EN TOMOPHTHOREAE OF THE UNITED STATES. 185

host, and extends on either side usually so as to invert the wings, turning them upside
down. (fig. 377). The color of the mass is more livid than is commonly the case in Km-
pusae and shows no variation towards a greenish hue. ‘The conidia are very variable,
usually strongly bent, and are readily distinguished by their neck-like basal portion. The
secondary conidia of the second type are remarkably regular in shape (figs. 362-365),
and of a type which differs widely from that of the primary spores.

A somewhat remarkable degeneration of the conidiophores was observed in, I think,
three instances. ‘The specimens in which this occurred were noticeably different in ap-
pearance from the usual conidial form, having a milky color and not presenting the usual
appearance of luxuriant growth. On examination the white substance in these speci-
mens proved to be composed of hyphae that had for the most part already broken up into
short pieces which were seen to produce at one extremity (figs. 366-367) the singular
bodies shown in figs. 368-69, of which the mass covering the insect was chiefly made up.
These bodies, which are about the size of the conidia, are almost invariably in the form of
an irregular kind of cross, the lateral outgrowths appearing at variable distances from
the extremities of the body; but always of about the shape represented in the figures
referred to. I saw no sign of any germination in them, though I was unable to make
proper cultivations, and I cannot explain their occurrence unless it be due to a degener-
ation of the mass of conidiophores, which subsequently attempt to fulfil their office in
this peculiar fashion. The specimens occurred in the usual situations in company with
the normal type, and the cause for the degeneration, if it be such, as well as for the pecu-
liar shape of the resulting bodies is not apparent, nor have I ever seen any condition re-
motely resembling this in other Empusae.

In the formation of zygospores it should be noted that, unlike the preceding species,
the conjugating hyphae are rarely, if ever, septate near the point of union, and are very
irregular, running into attenuated branches. The production of a spore from each of
the gametes (fig. 369) was sometimes noticed as well as the occurrence of double spores
(fig. 373a) apparently formed side by side. In one instance (fig. 368) conjugation
seemed to have occurred between the apices of hyphae and not by the usual Spirogyra-
like method.

Empusa (Entomophthora) gracilis nov. sp.
Pl. 21, figs. 379-391.

Conidia slender, subfusiform, with a neck-like papillate basal portion and attenuated
apex; strongly curved, rarely straight, containing large oil globules. Measurements
7-9 x 30-45, average 40 x 8,. Conidiophores digitate, coalescing over host in a white
mass. Oystidia of rare occurrence, rounded at the apex. Secondary conidia like the
primary; or nearly spherical, papillate. esting spores unknown. Host attached to
substratum by rhizoids.

Host. Diptera: on very minute gnats.
Habitat. Cullowhee, N. C.

Like ZH. variabilis, with which it is commonly associated, this species seems to attack

186 ROLAND THAXTER ON THE

only the minutest gnats and is thus very difficult to find. A small number of specimens
were taken at Cullowhee in July at different times; but I found it in no other locality
and it is apparently very rare. The conidia are very slender and readily separated from
those of 2. conica by their fusiform shape, neck-like basal portion and constantly smaller
size, the maximum length being slightly over 45,.

The species has no interest beyond the fact that it affords a second instance of the
peculiar “conica” type of conidia, and I can give no information concerning the resting
spores.

Empusa (Entomophthora) conica Nowakowski.
Pl. 21, figs. 392-410.

Entomophthora conica, Nowakowski l. ¢. A; /. c.B, p. 155, plates vir and rx, figs. 1-32.

Conidia long, slender, conical, often strongly curved with a rounded papillate base
tapering to the usually blunt extremity ; 25-80 x 10-14,. Conidiophores digitate, arising
as a rule directly from nearly spherical hyphal bodies and coalescing over the body of
the host in a clear white mass. Cystidia larger than conidiophores, rounded at apex.
Secondary conidia like the primary or broadly ovoid, rarely pomted at the apex. Rest-
ing spores, zygospores, produced by a Spirogyra-like conjugation, usually budding from
one of the gametes; spherical, colorless, 30-50, in diameter. Host attached to substra-
tum by numerous rhizoids.

Hosts. Diptera: imagines of Chironomus and other small gnats.

Habitat. Mt. Washington, N. H., North Carolina, Europe.

The singular shape of the conidia in this and the preceding species distinguishes them
at once from all other known Empusae although a transition from the ovoid type to this
elongate form is seen in HZ. sepulchralis, #. variabilis and HL. rhizospora. The exact ad-
vantage of such a shape it is difficult to understand as the spores do not seem so well
calculated to hit and adhere to a passing host as the more blunt forms. In contrast to
this elongate form the secondary conidia of the second type are extremely compact,
sometimes approaching those of 7. Muscae in shape. The separation of the conidium
proper from the mother cell wall is very commonly seen in this as in other species which
vegetate in very moist situations, and the tendency of the spore contents to become more
or less contracted is often observable; the contracted portion separating itself from
the empty extremity by a cross partition (fig. 396). The conidia themselves vary consid-
erably in size and shape, in the bluntness of their apices which I have never seen as sharply
pointed as is represented in Nowakowski’s plate, and in the relative thickness of the spore
and its amount of curvature. With regard to the curvature of this and other elongate
forms, a natural explanation seems to be afforded by the deviation of the conidiophores
from a perpendicular position which is usually more or less considerable except in the
upper middle portion of the mass. The conidia, while in process of formation, endeavor
to correct this deviation by curving upwards thus giving rise to the strongly curved —
elongate forms as well as to the abruptly bent bases so commonly seen in the ovispora
type. It is noticeable that this curvature is rarely, if ever seen in Empusae of the sphae-
rosperma type; and the reason for this is very evident in view of the peculiar mode of

ENTOMOPHTHOREAE OF THE UNITED STATES. 187

growth, already described in the last-named species, which characterizes the mass of co-
nidiophores as a whole, and allows the basidia to assume a vertical position which is
impossible in the rounded masses of the usual type.

In material of this species, where the growth of conidiophores has not been luxuri-
ant, the form of the conidia may be constantly such as is represented in figures 403-—
404; in fact the majority of the specimens obtained from Mt. Washington produced
spores of this nature. he affected hosts occurred in this locality on moss along the
borders of small brooks in the Alpine Garden, and only when the moss was completely
saturated with water, allowing an abundant growth of conidiophores, were the spores
of the usual elongate type. I have thought this worthy of mention, since the small
form might readily be taken for a distinct species. Although occurring in considerable
quantities on Mt. Washington, the species is somewhat rare in North Carolina where it
_isfound in company with Z. variabilis on saturated wood or stones in the beds of brooks
flowing through woods. It may be readily distinguished from the last-named species by
the clear white color of the mass of conidiophores.

The resting spores I have found in but few specimens, produced simultaneously with
the conidia by a process exactly similar to that described in /. sepulchralis.

This completes the enumeration of American Hmpusae at present known, and for con-
venience of reference I have added below a list of the European species which are
unrecorded from this country.

EUROPEAN SPECIES OF EMPUSA AS YET UNRECORDED FROM THE UNITED STATES.

Empusa Jassi, Cohn 1. c. B, p. 77. Sorokin J. c. C, p. 239. Schroeter J. ¢., p. 222.

This form, of which no complete description has ever been published, is referred to by
Cohn (J. ¢.B, pp. 76-77) in connection with his account of Zarichium megaspermum.
In this place he mentions that the spores are spherical and 20, in diameter, but gives no
specific name to the form, which, he states, occurs on Jassus 6-notatus. Where the name
Jassi first originated I am unable to say, and the species cannot be recognized without
further information regarding it. It may prove to be the species previously described as

__ £. apiculata which has many hosts, and it forms another element of confusion in the

group comprising 2. conglomerata, HL. Planchoniana, H. apiculata, LE. Jassi and per-
haps #. Tenthredinis. I quote below the note of Schroeter in his Silesian flora concern-
ing this species.

“330. Hmpusa Jassi, Cohn, 1870. Mycel im Kérper von Cicaden lebend, an den
todten Thieren als sammetartiger, weisser Schimmeliiberzug hervorbrechend. Conidien
kugelig, 20, Dehm.

Auf Jassus sex-notatus Mai, Juni.—Die todten Thiere haften den Grashalmen u. s. w.
fest an, die vier Fliigel wie zum Fluge ausgespreizt.—Breslau Schneitig 1869 in grosse
Menge.”

Entomophthora colorata Sorokin, J. c. C, p. 215, figs. 573, 623, 627; 1. c. D, p. 62, Pl. 11,
figs. 5-6, 19-27, Pl. rv, figs. 28, 28’. .

188 ROLAND THAXTER ON THE

This species which is said to occur on grasshoppers seems to be peculiar from its col-
ored conidial spores which, according to Sorokin, are reddish brown, round and resemble
those of H. Muscae except in color. The protoplasm from the basidium is discharged
with the spore. Sorokin states that it closely resembles #. Grylli, differing, however,
by its round and colored conidia. Itis in this species that Sorokin has observed peculiar
amoeboid bodies within the host which produce resting spores laterally or terminally.
For some further account of this species a review of Sorokin' may be found in Just’s
Bot. Jahresbericht (1881), p. 292, by Batalin.

Entomophthora Tipulae, Fresenius 1. ¢., B p. 206, figs. 46-50. Sorokin 7. ¢. ¢, p. 211,
fig. 651.

I find no mention of the occurrence of this species since it was described and figured
by Fresenius. The conidia are described as ovoid, with a short, broad, rounded, pro-
jecting base; measuring 33-40, in length. The figures represent a broad almost truncate
base and ovoid body which gives the spore a characteristic outline. The species was
found on a large Zipula which was wingless and adhering toarush. The mass of spores
and hyphae had a greenish brown color. ‘The form should be readily recognized by the
large size and peculiar shape of its spores, yet I have seen nothing like it on similar hosts
in this country.

Entomophthora Calliphorae, Giard 1. c.
Entomophthora muscivora (E#. Calliphorae Giard?), Schroeter 1. ¢., p. 223.

The species described by Giard on large flies (Calliphora) can, I think, hardly be dis-
tinct from the #7. muscivora of Schroeter since the rare peculiarity of a deep chestnut-
brown (marron foncé) resting spore, the measurements of which are the same (30, in
Calliphorae and 24-28, in muscivora) is common to both. The hosts and habit corre-
spond in the two forms, #. muscivora differing only in the fact that its conidia are also
described, while in 2. Calliphorae they were not observed. Schroeter describes the co-
nidia of his species as ovoid, with a blunt papilla; 20-24, long by 11-13, broad. On large
flies which are attached by numerous rhizoids. The conidia are slightly smaller than in
the form that I have described as . Americana from which it is separated by the pecu-
liarity of the resting spores. ;

Entomophthora ovispora, Nowakowski J. c. A; 1. c., B, p. 160, figs. 33-58. Sorokin J. e.
C, p. 235.

The conidia of this species almost exactly resemble those of 1. echinospora and #. Amer-
icana, being somewhat long-ovoid with papillate base and rounded apex. Like 7. Amer-
icana they contain numerous small oil globules of very regular size; but the species is
at once separated from either of the forms just mentioned by its peculiar cystidia which
are very large, resembling those of 7. sepulchralis (fig. 306). The conidia measure from
22,, to 28, in length by 14, in breadth. The resting spores are zygospores produced by
a Spirogyra-like conjugation and are of the usual type, 31, in diameter. The species —
occurs on flies: Lonchaca vaginalis, Syrphidae, Sapromyza, etc., and is found in wet
situations on damp ground, planks, ete.

SRT DE

ENTOMOPHTHOREAE OF THE UNITED STATES. 189

_ Lntomophthora curvispora, Nowakowski l. c. A; 1. c. B, p. 163, figs. 68-70. Sorokin /. e.
C, p. 233.

Under this name Nowakowski has described a form peculiar for its strongly curved
conidia, which are elongate, rounded at both extremities and measure 10-15, x 25-40p.
They resemble the curved forms occurring in /. variabilis, but are broader and more
rounded basally and much larger. The secondary conidia are represented as_ perfectly
spherical. ‘The resting spores are true zygospores produced by a Spirogyra-like conju-
gation; and of the usualform. The species is parasitic upon Simulia latipes, a small fly.

Tarichium megaspermum, Cohn l. c. B. Sorokin, 0. c. C, p. 235, figs. 600-602, 598, 599,
635-636. Schroeter J. c., p. 223.

This species is known only from its resting spores, which have been thoroughly de-
‘scribed and figured by Cohn, and is parasitic upon the larvae of Agrotis segetum which
are turned black by the disease. The resting spores are apparently azygospores borne
laterally or terminally from hyphae and are peculiar on account of their dark brown
epispore which is marked by sinuous furrows. The epispore is also frequently opaque
showing no furrows. The spores are spherical and of large size measuring from 34, to
55,, average 50,. The figures given by Sorokin are copied from Cohn’s plates and the
species has not, I believe, been noticed since its original description. It should be noted
that Z. virescens occurs in America on a similar host and may prove to be identical with
this species.

Entomophthora Phryganeae, Sorokin l. c. C, 239, figs. 578, 628 a, b.

Sorokin figures as characteristic of this species a long clavate body with a rhizoid-like
basal portion and a terminal round spore with a prominent rather narrow base of attach-
ment. In his text he states that the fungus was found on Phryganea grandis (June 26,
1881), growing only on the lower surface (between the first and second pair of legs as
indicated in the figure) being wholly superficial and not appearing within the body of the
host. The hyphae consist of two portions separated by a septum. The conidia are round
8X6-7,, the hyphae being 5, in breadth. The rhizoid-like basal expansion (by which the
hypha is apparently attached) is said to be characteristic. It is scarcely necessary to
remark that this can hardly be an Hmpusa and its position even among the Entomoph-
- thoreae seems very doubtful.

Sorokin remarks concerning this and the succeeding form, that he cannot vouch for
their distinctness from lack of material.

Entomophthora pelliculosa, Sorokin 1. ¢. €, p. 240, fig. 629.

Under this name Sorokin describes an Hmpusa found on a “flower fly,” Anthomyia
pagana.

“ The parasite resembles the ordinary #. Muscae, but the discharged conidia have the
strange peculiarity of being covered with several layers concentrically distributed, as
if a drop of protoplasm discharged simultaneously with the conidia had dried at several
different intervals forming each time something in the shape of an envelope. This char-
acteristic is so constant that all the conidia scattered along the substratum were sur-

MEMOIRS BOSTON SOC. NAT. HIST., VOL. IV. 27

190 ROLAND THAXTER ON THE

rounded by sharply defined concentric lines.” The figure represents a spore of the
Grylli type which bears little resemblance to that of H. Muscae, so that any determina-
tion based upon the figure and description is not possible.

Tarichia uvella, Krassilstchik l. ¢., p. 95.

Under this name Krassilstchik has described a fungus, growing in coleopterous lar-
vae, which is characterized by the production of a mass of brick-red “ Tarichium” spores
produced by a process not observed, and cohering in small, grape-like clusters as indi-
cated by the specific name. The spores are described as round, papillate, 8-10, in di-
ameter, surrounded by a wall of no great thickness. In a nutritive fluid they germinated
in four days, producing septate hyphae which after a week grew out of the culture fluid
and produced single, terminal, cylindrical, colorless spores, 9 X 3p.

This does not appear to be an Hmpusa from the course of development described, al-
though it might possibly be related to Massospora. Concerning this, it is, however, im-
possible to judge without figures or more detailed information concerning the species."

MASSOSPORA Peck.

Massospora cicadina, Peck l.¢., p. 44. Leidy, Proc. Acad. Nat. Sci., Phil. Vol. x, p. 235
(no name).

Conidia(?) produced from short hyphae or hyphal bodies, within the host; nearly spher-
ical to ovoid, tapering towards a small basal papilla of attachment; smooth or papillate-
verrucose, 10 X 18,-18 X 25,, forming a yellowish mass in the abdominal cavity ex-
posed as a coherent mass by the falling away of the abdominal rings. esting spores(?)
spherical, roughly reticulated, slightly colored, 38-50, in diameter (Peck). Host not
attached to substratum.

Hosts. Hemiptera: larvae, pupae and imagines of Cicada septendecem.

Habitat. New York, New Jersey, Washington, D. C., Illinois, Michigan, Texas.

This singular form should, I think, undoubtedly be placed among the Hntomophthoreae,
although it is decidedly anomalous in some respects. Professor Peck is inclined to place
it near Protomyces among the Coniomycetes; owing perhaps to the fact that the origin
of the spore mass from the characteristic entomophthoroid bodies (figs. 415-419) was
not apparent in the types. Whether these spores which fill the whole abdominal cavity
are morphologically similar to the conidia of Empusae, or are a kind of azygospore or
chlamydospore Iam unable to say, having examined only dried material in which it
was, of course, impossible to discover the exact process of formation and separation.
Their general appearance is certainly that of conidia; yet, unless a columella can be
demonstrated in connection with their formation they must be regarded as of a different

1 Entomophthora Anisopliae of Metschnikoff (Zeitschr. d. of Basidiomycetes which he calls Metarhizium. The names
Kaiserl. Landwirth, Gesell. f. Neurussland, Odessa, 1879, £. macrospora (De Bary Verg]. Morphol. d. Pilze) and 2,
pp. 21-50, with plate), which attacks coleopterous larvae, muscarina (Comptes Rendus, Vol. 89, p. 750) are appar-

is perhaps an Isaria, the spores measuring 4.8 X 1.64. It is ently printers’ errors.
placed by Sorokin (7. c. C, p. 268) as belonging to a genus

ENTOMOPHTHOREAE OF THE UNITED STATES. 191

nature. Of these spores there are two kinds usually to be seen in preparations: a larger
form nearly resembling an Hmpusa conidium and possessing a perfectly smooth outer
wall (figs. 421-423) ; and a second form, thicker walled, smaller, distinctly papillate in
most instances, but produced similarly from hyphal bodies (figs. 424-428). The devel-
opment of these spores after formation is wholly unknown, although there can be little
doubt that they furnish the immediate means of spreading the disease. It should be
noted that the anterior portion of the host’s body is wholly free from fungus in the spec-
imens which I have examined. The host may thus live for a considerable time after the
abdominal rings have begun to fall away and in this manner disseminate the spores by its
own movements. That this is the fact seems certain from the observations of Professor
French, who writes me that he has seen both larvae and imagos of the locust moving
about at Carbondale, Ill., in the condition just described. The probable development of

the spores after falling from the host may be inferred from analogy with Empusae gen-
erally, and would naturally consist in the production of secondary conidia discharged as
in Empusae, and affording the direct means of infection. The smaller type of spore
from the considerable thickness of its walls is manifestly adapted to await uninjured the
occurrence of conditions favorable to its germination and the hypothetical course of de-
velopment given above would thus result in a dissemination perhaps quite as effectual as
in the usual course adopted by Empusae.

T have included as “resting spores ” a second type of spore described by Peck as oc-
eurring in certain individuals, although never having seen these spores I am unable to
determine whether I am right in so domg. The description quoted gives no note of
either their shape or origin, so that I am only justified in considering them resting spores
from their analogy to similar spores in H’mpusa.

The distribution of the species is apparently wide, and a further study of the facts
connected with its history and development should be full of interest. Whether the fun-
gus is adapted to a subterranean existence, attacking the larvae during their seventeen
years of existence and thus appearing subsequently on the fully developed host, or whether
it is continued for this long period by resting spores (a supposition highly improbable),
or by the infection of isolated specimens of the same or nearly allied hosts which continue
the infection during this period, is quite uncertain. It is apparently liable to appear
wherever the Cicada is known, as shown by the localities above mentioned. I am in-
debted to the kindness of Mr. L. O. Howard for specimens received from Michigan which,
‘together with an example in Dr. Farlow’s herbarium from Texas are the only specimens

which I have examined.’

BASIDIOBOLUS Eidam (1885).

Basidiobolus Ranarum, Hidam 1. c. Schroeter l. ¢., p. 224.
Conidia nearly spherical to suboyoid, tapering slightly to a rounded base from which

the small sharply pointed papilla of attachment projects abruptly. Average measurements
1 The above was in press before the author had seen the in which he places the present genus among the Ento-

excellent summary of contagious insect diseases by Prof. mophthoreae.
__§. A. Forbes (Psyche, Vol. v, pp. 3-12, Cambridge (1888)),

192 ROLAND THAXTER ON THE

37 x 40,40 x 45,. Conidiophores arising from single cells of hyphae, simple, much swol-
len terminally, this swelling developing into a peculiar piece, the basidium, which is dis-
charged with the spore. Secondary conidia like the primary, sometimes produced on a
capillary conidiophore. esting spores, zygospores, spherical, with an irregularly pitted
or folded epispore; 25-45 in diameter; pale orange yellow or nearly colorless, sometimes
opaque from a dark brown incrustation of the epispore; produced by the conjugation of
two adjacent cells of a hypha, or of two conidial spores, through the absorption of the in-
tervening cross partition; the union being preceded by the appearance of two finger-like
projections, one from either cell, which are applied to one another and, becoming septate
near their tips, persist as appendages to the mature spore.

On the excrement of frogs.

Habitat. Cambridge, Mass.; Europe.

Beyond the hitherto unrecorded occurrence, in America, of this most interesting form,
I have nothing new to add to the admirable monograph of Eidam above cited. The
fungus appeared on the excrement of frogs kept in the biological laboratory at Cam-
bridge for purposes of dissection, and was obtained by filtering the water in which the
frogs were kept and placing the sediment in a tin box. J was unable at the time to make
artificial cultivations of the spores, by means of which the studies of Hidam were carried
out, and the figures given on plate 21 are derived from specimens growing on the nat-
ural substratum of the fungus. It is probably for this reason that the production of zyg-
ospores seems to vary slightly from that described by Hidam, in that they appear to be
formed near the branched extremities of very large and sparingly septate hyphae. The
early stages ofthe process I did not observe, and for a complete morphological history of
the species the beautiful plates of Eidam should be consulted.

LIST OF PAPERS CONSULTED.
American.
Axrruur, J. C. A. Ona new larvae Entomophthora. Bot. Gazette, Vol. xt, p. 14 (1886), with plate.
B. Entomophthora Phytonomi in Bull. N. Y. Agr. Exp. Station, Jan., 1886, with cut.
Brssry, C. E. A new species of insect-destroying fungus. Amer. Naturalist, Vol. xvi, pp. 1280 and 1286 (Dec., 1883).

Pics, C. H. Massospora cicadina n. g. et sp. 31st Rep. of State Botanist of N. Y., p. 44 (1879).
In addition to the above one or two catalogue references to Z. Muscae and E. Calopteni.

European.

Batu. Ueber Pilzepizootien der forstverheerenden Raupen. Schriften der naturforschenden Gesellschaft zu Danzig, neue
Folge, Band 1, Heft 2, Danzig (1869).

Braun, A. Algarum unicellularum genera nova et minus cognita. Leipsic (1855), p. 105.

BrEFELD, O. A. Entwickelungsgeschichte der Empusa Muscae und Empusa radicans. Botanische Zeitung, xxvim, pp. 177
and 161 (1870).
B. Untersuchungen ueber die Entwicklung der Empusa Muscae und £. radicans. Abhandlung der Naturforsch-
enden Gesellschaft zu Halle, Bd. xu, Heft 1, p. 1 (1871). Plates.
C. Ueber die Entomophthoreen und ihre Verwandten. Botanische Zeitung, xxxv, pp. 345 and 368 (1877).
D. Entomophthora radicans. Botanische Untersuchungen ueber Schimmelpilze, Heft rv, p. 97, Leipzig (1881).
Plate.

H. Conidiobolus utriculosus und C. minor. Botanische Untersuchungen ueber Schimmelpilze, Heft v1, p. 35,
Leipzig (1884). Plates.

ENTOMOPHTHOREAE OF THE UNITED STATES. 193

Coun, F. A. Hmpusa Muscae und die Krankheit der Stubenfliegen. Nova Acta Academiae Caesareae Leopoldino- Carol-
olinae Germanicae Naturae curiosorum, xxv, Abh. 1, p. 301, Dresden (1855). Plates.
~ B. Ueber eine neue Pilzkrankheit der Erdraupen. Beitrage zur Biologie der Pflanzen, Band 1, Heft 1, p. 58;
(1875). Plates.
Cornu, M. A. Note sur une nouvelle espéce d’Hntomophthora. Bulletin de la Société Botanique de France, xx, p. 189,
Paris (1873).
B. Epidémie causée sur des Diptéres du genre Syrphus par un champignon Entomophthora (Cornu et Brongniart)
Association Francaise pour l’Avancement des Sciences, Congrés de Paris, p. 4; August (1878).

Erpam, E. Basidiobolus, eine neue Gattung der Entomophthoraceen. Beitrage zur Biologie der Pflanzen, Band tv, Heft 2
p. 181, Breslau (1886). Plates.

?

Fresenius, G. A. Notiz, Insekten-Pilze betreffend. Botanische Zeitung, Band xrv, p. 882 (1856).
B. Ueber die Pilzgattung Zntomophthora. Abhandlungen der Senkenbergischen naturforschenden Gesellschaft,
Band uy, Lieferung 2, p. 201, Frankfurt (1858). Plate.

Frims, E. Sporendonema Muscae. Systema mycologicum, Band m1, p. 435, Gryphiswaldae (1829).

Grarp, A. Deux espéces d’Hntomophthora nouveaux pour la flore de France. Bulletin Scientifique du département du
Nord, Série 2, deuxi¢me annee, No. 11, p. 353, Lisle.

Krassitstscuix, I. On diseases of insects caused by vegetable parasites. Mémoires de la Société des Naturalistes de la
nouvelle Russie, Vol. x1, part 1, p. 75. Odessa (1886). (Jn Russian.)

Kurzine, F. T. Saprolegnia minor. Phycologia generalis, p. 157, Leipsic (1843).

Lrgert, S. Die Pilzkrankheit der Fliegen. Verhandlungen der Ziircherischen naturforschenden Gesellschaft, Oct. 29,
1856. Plates.

Lonprt, G. Einige neue parastische Pilze. Tageblatt der Naturforschenden Versammlungen zu Breslau (1874).

LeirGes, H. Completoria complens ein in Farnprothallien schmarotzender Pilz. Sitzungsberichte der Kaiserlichen Akad-
emie der Wissenschaften. 84, Abth. 1, Wien (1882). Plate.

Nowakowsk1, L. A, Die Copulation einiger Entomophthoreen. Botanische Zeitung, Band xxxv, p. 217 (1877).
B. Entomophthoreae, etc. Proceedings of the Krakow Academy of Sciences (in Polish), 1883, p. 153. Plates.

Pariurs, W. Entomophthora ferruginea. Annals and Magazine of Natural History, series 5, Vol. xviu, p. 4 (July, 1886)
Plate.

Rosin, C. Histoire naturelle des Végétaux parasites qui croissent sur Homme et sur les Animaux vivants, avec Atlas de
15 Planches, Paris (1853).

Scurorter, J. Entomophthorei. Kryptogamen-flora von Schlesien, Band 11, Lieferung 2 (Pilze), p. 217, Breslau (1886).

Soroxin, H. A. Vorlaiufige Mittheilung tiber einige neue Hntomophthora-Gattungen. Hedwigia, Vol. xv, p. 146. Dresden
(1876).
B. Ueber zwei neue Entomophthora-Arten. Beitrage zur Biologie der Pflanzen, Band nu, Heft 3, p. 387. Plate.
C. Entomophthora. Vegetable parasites of man and animals as a cause of contagious diseases. Vol. 0, p. 291,
St. Petersburg (1883). Plates. (Jn Russian.)
D. Entomophthora colorata, Aphidis and rimosa. Memoirs of the Imperial Academy of Sciences, Vol. xxxvu,
Book 1, p. 58, St. Petersburg (1880). Plate. (Jn Russian.)

Winter, G. Zwei neue Entomophthoreen-Formen. Botanisches Centralblatt, Band v, 2, p. 62 (1881). (To this should
be added Winter’s enumeration of Entomophthoreae in Rabenhorst’s Kryptogamen-Flora, Band I, p. 74, Leipsig
(1884), references to which have been inadvertently omitted in the text).

194

ROLAND THAXTER ON THE

DESCRIPTIONS OF THE PLATES.

** The following figures are, with the exception of those representing host insects, from camera drawings slightly reduced

by photography and done on stone from the negatives.

Figures marked with an asterisk were magnified 230 diameters

approximately in the original drawings; and the remainder, with the exception of the host insects, were magnified 435

diameters approximately.

*Fig 16
Fig 2.
Fig 3.
Fig 4.
Figs. 5-6.
Figs. 7-8
Fig. 9
Fig. 10.
Figs. 11-12.
Fig. 13.
Fig. 14
Fig. 15

*Fig. 16

*Fig. 17

*Fig. 18

*Fig. 19.

*Fig. 20.
Figs. 21-24.
Figs. 25-28.
Figs. 29-30.

*FRigs. 31-35.

*Fios. 36-39.

*Fig 40.

*Fig. 41.

*Fig. 42.

*Fig 43.

*Fig. 44,

*Fig. 45.

*Fig. 46.
Fig. 47.
Fig 48.
Fig 49,
Figs, 50-55.
Figs. 56-59.
Figs. 60-61.
Fig. 62.

PLATE 14.
Empusa Muscae, figs. 1-9.
Group of conidiophores showing conidia in several stages of development.
Basidium after the discharge of the conidium.
Basidium bearing conidium before discharge.
Hyphal body germinating within the host.
Conidial spores discharged upon a slide and surrounded by a mass of protoplasm from the basidium.

Secondary conidia of the second type (unlike the primary).
Secondary conidium of the second type before discharge from the primary conidium.

Empusa Culicis, figs. 10-16.
Group of conidiophores.
Primary conidia two of which are surrounded by a mass of protoplasm, the two others (@@) being free.
Secondary conidium of the second type before discharge from the primary conidium.
Secondary conidium of the second type.
Two chlamydospores formed within the host.
A rhizoid formed by the adhesion of two filaments.

Empusa Grylli, figs. 17-48.
Group of conidiophores of different ages which have separated themselves from the empty hyphae left
behind, by successive cross partitions.

Conidium before discharge from the basidium.

Upper part of basidium after discharge of the conidium showing the columella as a rounded prominence.

Primary conidium producing a secondary conidium of the asual type.

Conidia from grasshopper (Acridian).

Conidia from hairy caterpillar (Arctian).

Conidia from wood cricket (Ceuwthophilus).

Successive stages in the formation of resting spores by a possibly sexual process.

Variations in the process of forming resting spores by the method figured in figs. 31-35.

Production of a terminal resting spore asexually from a culture of chlamydospores taken from a caterpillar
and made to develop in water upon a slide.

A resting spore of irregular shape formed by incomplete budding from a hypha.

A resting spore produced within a hyphal body.

A resting spore in process of budding from a hyphal body.

A mature resting spore.

Two septate hyphae taken from the femur of an Acridian, showing a point of anastomosis and numerous
small outgrowths together with the lateral production of a resting spore.

A chlamydospore germinating.

A resting spore rendered double by the imperfect union of the two divisions of a hyphal body.

An Acridian attacked by Z. Grylli, after remaining a few hours in a moist chamber.

PLATE 15.

Empusa Tenthredinis, figs. 49-55.

Secondary conidium in process of formation from a primary spore.
Primary conidia froma species of Tenthredo.

Empusa conglomerata? figs. 56-62.
Primary conidia from larve of Tipula sp.
Resting spores in process of formation by budding from hyphal bodies nearly spherical in shape, from
the same host.
Mature resting spore.

*Fig. ~ 68.
*Fig. 64.
Fig. 65.
Figs. 66-68.
Fig. 69.
Fig. 70.
Figs. 71-73.
*Fig. 74.
*Fig. 75.
Figs. 76-78.
Figs. 79-81.
*Fig. 82.
Fig. 83.
Fig. 84,
Figs. 85-89.
Fig. 90.
*Fig. 91.
Fig. 92.
Figs. 93-94.
Figs. 95-103.
Fig. 104.
Fig. 105.

*Figs. 106-108.

Fig. 109.
Fig. 110.
Figs. 111-116.
Fig. 117.
Fig. 118.
Fig. 119.
Fig. 120.

Figs. 121-122.
Figs. 123-124.

Fig. 124.
Fig. 125.
Fig. 126.
Fig. 127.
Figs. 128-140.
Fig. 129.
Fig. 130.

ENTOMOPHTHOREAE OF THE UNITED STATES. 195

Empusa apiculata n.s., figs. 63-75.
Conidiophores tending to become digitate. From small fly.
Simple conidiophore arising directly from a rounded hyphal body. From small fly,
A primary conidium germinating and producing a secondary conidium. From small fly.
Primary conidium from small fly.
Conidium from deltoid moth.
Conidium from caterpillar of Hyphantria.
(Var. Major), primary conidia from beetle (Ptilodactyla serricollis).
Resting spore in process of formation from short hyphae here associated with a cross partition.
Geometrid moth.
Terminal portion of a rhizoid from small fly.

From

Empusa Planchoniana ? figs. 76-81.

Primary conidia from aphides, fig. 77 having a slight apiculus.
Resting spores forming interstitially and terminally from hyphae.

Empusa papillata n. s., figs. 82-90.

Conidiophores.

Secondary conidium in process of development from a primary spore. The columella is forced into the
secondary spore probably in this case by the contraction of its contents, the primary spore being
empty.

Terminal portion of a rhizoid.

Primary conidia.

A mature resting spore.

PLATE 16.

Empusa Caroliniana n. s., figs. 91-105.

Conidiophores, one arising directly from a hyphal body.

A hypha the contents of which have become contracted into hyphal bodies.
Primary conidia from fresh material.

Primary conidia as they appear in dried material.

Secondary conidium in process of formation from a primary spore.

A mature resting spore. All these figures are from Tipula sp.

Empusa (Triplosporium) Fresenii (figs. 106-140).

Masses of nearly naked protoplasm from which the hyphal bodies (fig. 127) are formed.

Conidium before discharge from the basidium.

Conidium germinating in the ordinary way.

Primary conidia.

A secondary conidium of the second type produced from a primary conidium, on its capillary coni-
diophore.

A secondary conidium of the second type produced from a conidiophore which is neither capillary nor of
the usual type.

A secondary conidium of the second type, borne on a capillary conidiophore, which has begun to germi-
nate before separating from it.

A secondary conidium of the second type germinating laterally by a capillary conidiophore.

Secondary conidia of the second type germinating from their apices in the usual manner.

Secondary conidia of the second type.

A primary conidiophore producing three capillary conidiophores, the middle one beginning to swell into
a spore.

A hypha of germination of the usual type, from a primary conidium, has sent up a capillary conidiophore
at the tip of which a secondary conidium of the second type is beginning to form.

A hyphal body germinating to form a conidiophore.

Two hyphal bodies taken from a mass filling the abdomen of Aphis.

Two hyphal bodies lying side by side previous to conjugation begin to show slight prominences on their
upper inner sides.

These prominences have become gametes which have come in contact with one another midway between
the two hyphal bodies.

The partition wall between the gametes has wholly or partially disappeared and a bud has begun to ap-
pear rising upwards from their point of union.

Figs. 131-134.
Figs. 135-136.
Fig 137.
Fig 138.
Figs. 139-140.
*Fig. 141.
*Fig. 142.
Fig 143.
Figs. 144-145.
Figs. 146-154.
Fig 155.
Figs. 156-157.
Figs. 158-160.
*Fig 161.
Figs. 162-166.
Figs. 167-171.
Fig 168.
Figs. 169-170.
Fig. 172.
Fig 173.
Fig 174.
Fig 175.
Figs. 176-177.
Fig 178.
*Fig Ie)
*Fig 180.
Fig 181.
Figs. 182-184.
Figs. 185-189.
Fig 190.
Fig. 191.
Fig. 192.
Fig 193.
Fig 194,
Fig 195.
Figs. 196-199.
Fig 200.
Fig 201
*Fig 202

ROLAND THAXTER ON THE

Showing this bud in several successive stages of development.

The bud has become the mother cell of a zygospore while the two hyphal bodies remain attached as
bladders which contain certain fatty bodies.

A mature zygospore lying free in its mother cell, the walls having béen separated through the absorption
of water.

A small zygospore to which the ragged remnants of the hyphal bodies are still attached as in the previous
figure.

Zygospores from which the remnants of the hyphal bodies have wholly disappeared, a remnant of the
gametes still adhering to fig. 140.

Empusa (Triplosporium) lageniformis n. s., figs. 141-160.

Young conidiophores of a digitate type seldom seen in this species. All the figures are from Aphides on
white birch (3. populifolia).

Conidiophores of the usual type.

A primary conidium of the usual type germinating to produce a secondary conidium of the first type.

Hyphal bodies germinating to form conidiophores.

Primary conidia.

A primary conidium has produced a capillary conidiophore, the apex of which has begun to swell into a
secondary conidium of the second type.

Two primary conidia have produced capillary conidiophores upon which are borne mature secondary co-
nidia of the second type.

Three secondary conidia of the second type in different stages of germination.

PLATE 17.

Empusa (Entomophthora) Lampyridarum n. s., figs. 161-172.

Conidiophores of a simple type. The type of the species is however probably compound.

Primary conidia.

Secondary conidia of the second type.

A secondary conidium of the second type has produced a capillary conidiophore the apex of which is be-
coming swollen into a tertiary conidium of the same type.

Two primary conidia bearing mature secondary conidia of the second type on capillary conidiophores.

Appearance of host, Chauliognathus Pensylvanicus, attacked by this species.

Empusa (Entomophthora) geometralis n. s., figs. 173-178.

Eupithecia attached to a pine needle by haustoria before death.

Thera similarly attached showing position of conidiophores.

Group of primary conidia.

Two primary conidia producing secondary conidia of the second type on capillary conidiophores.
Two secondary conidia of the second type.

Empusa (Entomophthora) occidentalis n. s., figs. 179-199.
Rhizoid with irregularly expanded extremity.
Digitate conidiophore.
Basidium and conidium before discharge.
Primary conidia with fat globules.
Primary conidia of the usual appearance. Figs. 183 and 185 are more distinctive of the species.
Primary conidium which has germinated to produce a secondary conidium of the first type.
Primary conidium which has produced a capillary conidiophore on which is borne a mature secondary
conidium of the second type.
Primary conidium germinating as in the last figure: the [oe conidium being immature.
Secondary conidium of the second type.
Secondary conidium of the second type in process of germination.
Mature resting spore.
Formation of resting spores by a possible sexual process.

Empusa (Entomophthora) sphaerosperma, figs. 200-219.
Colias attacked by the fungus.
A small hymenopterous insect similarly attacked.
A compound conidiophore.

ENTOMOPHTHOREAE OF THE UNITED STATES. 197

Fig. 203. Primary conidia from small gnat,

Fig. | 204. Thesame from Thrips sp.

Fig. 205. The same from a species of Musca.

Fig. 206. The same from an ichneumon.

Fig. 207. The same from Colias philodice.

Fig. 208. The same from Phytonomus larva.

Fig. 209. The same from rose leaf-hopper ( Typhlocyba).

Fig. 210. A primary conidium producing a capillary conidiophore on which is borne a mature secondary conidium
of the second type.

Fig. 211. Thesame. The secondary conidium in process of formation.

Fig. 212. A’secondary spore of the second type unusually long.

Fig. 213. A secondary conidium of the second type of the usual form.

Figs. 214-216. Resting spores in process of formation from short hyphae, associated with a cross partition in each
case.

Fig. 217. Resting spore in process of formation from a single short hypha.

Figs. 218-219. Mature resting spores.

PLATE 18.
Empusa (Entomophthora) Aphidis, figs. 220-240.

*Fig. 220. Compound conidiophore.
*Fig. 221. Cystidium.
Fig. 222. Simple conidiophore: the protoplasm in the basidium has separated itself from the empty hypha below

by successive cross partitions.
Figs. 223-236. Primary conidia,

Fig. 237. ‘Two secondary conidia of the second type.
Fig. 238. A primary conidium bearing a secondary conidium of the second type.
*Fig. 239. <A hyphal body germinating in all directions.
Fig. 240. A primary spore germinating in water, the protoplasm separating itself by cross partitions from the empty
hypha.

Empusa (Entomophthora) dipterigena n. s., figs. 241-250.
Figs. 241-247. Primary conidia froma small fly, figs. 243 and 244 being characteristic of the species.

Fig. 248. Primary conidium bearing a secondary conidium.
*Fig. 249. Rhizoid with terminal expansion. The divisions of the expansion should be more truncate.
Fig. 250. A mature resting spore produced externally.

Empusa (Entomophthora) virescens n. s., figs. 251-261.

Fig. 251. Digitate conidiophore.
Figs. 252-259. Conidia.

Fig. 260. Conidium which has been discharged without the rupture of the mother-cell wall which has merely
stretched.
a hic. 261. Hyphal bedy germinating in all directions.

Empusa (Entomophthora) Americana nu. s., figs. 262-273.

*Fig. 262. A group of rhizoids.

Figs. 263-271. Conidia. :
“« 972-273. Two mature resting spores; fig. 272 showing separation of the inner and the two outer walls.

Empusa (Entomophthora) montana n. s., figs. 274-285.

| *Fig. 274. A digitate conidiophore produced directly from a chlamydospore.
*Fig. 275. Two cystidia.
*Fig. 276. Terminal portion of a rhizoid showing its attachment to a bit of Sphagnum.
Fig. | 277. Gross appearance of the fungus many times enlarged.

Figs. 278-285. Conidia.

PLATE 19.
Empusa (Entomophthora) echinospora n. s., figs. 286-305.

Figs. 286-294. Conidia.
. Fig. 295. Terminal portion of a rhizoid.

MEMOIRS BOSTON SOC. NAT. HIST., VOU. TV. 2s

Fig. 296.
Fig. 297.

gs. 298-299.

Fig. 300.
Figs. 301-302.
Figs. 303-304.
Fig 305.
*Fig. 306.
*Fig. 307.
*Fig. 308.
Fig. 309.
Figs. 310-317.
Figs. 318-319.
Fig. 320.
Fig. 321.
*Fig. 322.
*Figs. 323-325.
Fig. 326.
*Fig. 327.
*Fig. 328.
Figs. 329-342.
Fig. 343.
Fig. 344.
Fig. 345.
Fig. 346.
i: 347.
*Fig. 348.
Figs. 349-360.
Fig. 361.
Fig. 362.

Figs. 363-365.
Figs. 366-367.

Figs. 368-369.
*Fig. 370.
*Fig. 371.

*Figs. 372-373.

*Fig. 374.
Fig. 375.
Fig. 376.
Fig. 377.
Fig. 378.

*Fig. 379.
Fig. 380.

ROLAND THAXTER ON THE

A zygospore which seems to have resulted from a double conjugation.

A group of sporophores emerging from the host’s body previous to the formation of zyg gospores. One of
their number has grown beyond the rest and subsequently forms part of a network which holds the
mass of external zygospores.

Two instances of external conjugation.

Conjugation taking place within the host.

Further examples of external conjugation.

Resting spores formed internally, the process of conjugation not visible.

Mature resting spore.

Empusa (Entomophthora) sepulchralis n. s., figs. 306-326. © -

A eystidium somewhat immature.

The terminal portion of a cystidium at a more advanced stage.

A digitate conidiophore arising directly from a spherical hyphal body.

A hyphal body beginning to germinate.

Primary conidia.

Secondary conidia of the second type.

Primary conidium in which the mother-cell wall has separated from the spore, remaining attached only at
its point of dehiscence from the basidium.

Primary conidium in which the separation from the inother-cell has become complete.

Conjugation of two hyphae and first budding of the zygospore from one of the gametes.

Several stages in the formation of a zygospore. In fig. 325 the whole contents of the conjugating cells
have passed into the zygospore.

Mature zygospore. (The circles of dots are due to careless engraving).

PLATE 20.

Empusa (Entomophthora) variabilis n. s., figs. 326-315.
Compound conidiophore.
Rhizoids.
Primary conidia.
Primary conidia among tlre first discharged.
Formation of a secondary conidium of the first type.
Formation of a secondary conidium of the second type.
Secondary conidium of second type.

Empusa (Entomophthora) rhizospora n. s., figs. 347-378.

Conidiophore arising from spherical hyphal body.

Cystidium.

Primary conidia.

Production of secondary conidium of the first type.

Production of secondary conidium of the second type.

Secondary conidia of the second type.

Production of ‘ pseudoconidia” from hyphal bodies resulting from the general degeneration of the co-
nidiophores.

Two of the pseudoconidia fully developed.

Formation of a zygospore by the conjugation of the free ends of two hyphae. :

Spirogyra-like conjugation resulting in the production of a spore from both gametes. . .

Two similar points of conjugation in which the rhizoid-like enveloping processes are developing from the
base of the spore.

Group of mature zygospores showing indurated hyphae and rhizoid-like processes.

A single zygospore.

A zygospore freed from the epispore.

A ‘* Caddis fly” showing the growth of conidiophores.

Gross appearance of the zygospores produced externally over the host.

PLATE 21.

Empusa (Entomophthora) gracilis n. s., figs. 379-391.
Conidiophore.
Production of secondary conidium of the first type.

a eee eee

ENTOMOPHTHOREAE OF THE UNITED STATES. 199

Fig. 381. Secondary conidium of the second type.
Figs. 382-391. Primary conidia.

Empusa (Entomophthora) conica, Nowakowski, figs. 392-408.

*Fig. 892. Conidiophore originating from spherical hyphal body.
Fig. 393. Cystidium.
- Figs. 394-402. Primary conidia.
Figs. 403-104. Primary conidia produced in dryer situations.
Fig. 405. Production of secondary conidium of the first type.
Figs. 406-407. Secondary conidia of the second type.
Fig. 408. Production of secondary conidium of the second type.
*Fig. 409. Production of a zygospore by Spirogyra-like conjugation.

Basidiobolus Ranarum, EHidam, figs. 140-144.

Fig. 410. Conidiophore with conidium budding from its apex.
Fig. 411. Conidium still connected with the basidium.
Fig. 412. The basidium (@) Separated from the conidium.

Figs. 413-414. Zygospores in different stages of development with the “ nabel’” (a,a), persistent.

Massospora cicadina, Peck, figs. 415-429.

Figs. 415-417. Hyphal bodies.

Figs. 418-420. Production of spores from hyphal bodies.
Figs. 421-423. Spores of the larger and smooth type.

Figs. 424-428. Spores of the usual type.

Fig. 429. Que of the same spores seen in optical section,

Notr.—The present investigation was carried on in the Cryptogamic laboratory of Harvard University and was pre-
sented as a graduating thesis May 1, 1888.

CONTENTS.

Summary of Entomogenous plants, t ate WE Secondary conidia, 5 4 : 145
Facultative parasites of insects, 136 Cystidia and rhizoids, 3 - 5 aie
Entomophthoreae : Formation of zygospores and azygospores, 146
General characters, . 6 : ‘ 136 Hosts of Empusae, : A 3 150
The genus Completoria, ! : oe. dee The habitat of Empusae, 5 5 aig
The genus Conidiobolus, fe - : 137 Miscellaneous notes, . : 4 CB
The genus Basidiobolus, . : - 1388 Subgenera of Empusa, 5 3 - 152
The genus Empusa: Systematic enumeration of species :
Infection and production of hyphal bodies, 139 American species of Empusa, : = . 155
Germination of the hyphal bodies and chla- European species of Empusa, : E 187
mydospores, 5 Z - 141 Massospora : 3 ¢ ke 190
Formation of nodiaigohores, Al es Basidiobolus - - E 4 191
Formation and discharge of the tanita: 143 List of papers consulted . 4 5 192

The conidia and their germination, . a) orld

200

ROLAND THAXTER ON THE

INDEX OF GENERA AND SPECIES.

Appendicularia entomophila, 135.
Aspergillus, 136.

Basidiobolus, 186, 138, 148, 150.
B. ranarum, 191.
Botrytis Bassiana, 136.

Completoria complens, 137.
Conidiobolus, 137, 139, 140, 148. 150.
C. utriculosus, 138.
C. minor, 138.
Cordyeeps, 135, 136.
C. armeniaca, 136.

Empusa, 139, 153, 154.
E. Americana, 179, 177, 180, 181.
KE. Aphidis, 175, 140, 142, 151, 153, 165, 166, 178
E. apiculata, 163, 142, 148, 158, 165, 167, 187.

i. anlicae, 159, 162.

{. Calliphorae, (188) 149, 179.

E. Calopteni, 159.

EK. Caroliniana, 167, 155.

E. colorata, (187) 140, 168.

E. conglomerata, 162, 142, 159, 161, 164, 166, 187.
KE. conica, 186, 141, 147, 151, 153, 182, 183.

EH. Culicis, 157, 143, 153, 165.

E. curvispora, (159) 140, 147, 153, 182.

E. dipterigena, 177, 175, 180, 181.

KE. echinospora, 180, 146, 148, 149, 177, 179.

EK. Freseniana, 168.

Kk. Fresenii, 167, 140, 145, 148, 149, 151, 152,

169, 176.
. geometralis, 170, 151.
- gracilis, 185, 144, 15).

Se &

165, 166, 173, 188.
. Jussi, 187, 164.
. lageniformis, 169, 151, 152, 171.
. Lampyridarum, 169, 155.
. macrospora, 190.
. major, 164.
. Megasperma, (18!) 149, 178.
. Montana, 180.

. muscarina, 190.

- muscivora, (188), 149, 179.
occidentalis, 171, 147, 161, 169. 175.

. ovispora, (188), 140, 147, 177, 179, 182.
. papillata, 166, 151, 153.

. Planchoniana, 165, 164, 187.

. radicans, 172, 145, 150.

. rimosa, 177.

. rhizospora, 183, 149, 182, 186.

. sepulchralis, 181, 141, 179, 186, 187.

158, 164, 171.
. Tenthredinis, 162, 187.
. Tipulae, (188).
. variabilis, 183, 151, 186, 187, 189.
. virescens, 178, 142, 189.
Enterobryus, 135.
Entomophthora, 153.

E. Americana, 179.

Sees

. Grylli, 159, 140, 148, 149, 150, 152, 153, 162, 163,

. Museae, 155, 141, 142, 144, 151, 153, 186, 188, 189.

. sphaerosperma, 172, 140, 145, 147, 150, 151, 152,

E. Anisopliae, 190.
Kk. Aphidis, 175.

E. aulicae, 159.

KE. Calliphorae, 188.
K. Calopteni, 159.

BE. colorata, 187.

IK. conglomerata, 162.
BK. conica, 153, 186.
E. Culicis, 157.

Ki. curvispora, 153.
K. dipterigena, 177.
IX. echinospora, 180.
E. geometralis, 170.
E. gracilis, 185.

E. Grylli, 159.

K. Jassi, 187.

EK. Lampyridaruin, 169.
E. montana, 180.

KE. Muscae, 155.

E. muscivora, 188.

E. occidentalis, 171.
E. ovispora, 153, 188.
E. Planchoniana, 165.
E. pelliculosa, 189.
K. Phryganeae, 189.
EK. radicans, 153, 172.
E. rimosa, 177.

E. sepulchralis, 181.
E. sphaerosperma, 172.
E. Tenthredinis, 162.
E. Tipulae, 188.

E. variabilis, 183.

E. virescens, 178.

Isavia, 136, 190.

Laboulbenia, 135.
Lamia, 153.
L. Culicis, 157, 153.

Massospora, 137, 189, 190.
M. cicadina, 190.
Metarhigium, 190.
Myiophyton, 154.
M. Cohnii, 155.

Penicillium, 136.
Piptocephalis, 149.
Protomyces, 190

Succharomyces, 154.
Saprolegnia minor, 157.
Sporendonema, 154.

S. Muscae, 1°5.

Tarichium, 139, 149.
T. Aphidis, 175.
T. megaspermum, 189, 187.
T. sphaerospermum, 172.
T. uvella, 190.
Triplosporium, 152.
T. Fresenii, 167.
T. lageniformis, 169.

ee Ak li i i a

<P aeey

ENTOMOPHTHOREAE OF THE UNITED STATES.

INDEX OF HOST-INSECTS,

Acridians, 159. Lepidoptera, 159, 164, 171, 172, 178.
Agrotis fennica, 178. Limnophilus, 172.

A. segetum, 189. Lonchaea vaginalis, 188.
Anthomyia, 156. Lucilia Caesar, 155, 179.

A. pagana, 189. Musca, 155, 172.
Aphides, 165, 168, 169, 171. M. domestica, 155, 172,
Aphis, 172. M. vomitoria, 179.

A. mali, 168. Mycetophelidae, 172, 177.
Arctians, 159. Neuroptera, 172.
Bug, 177. Orgyia nova, 159, 161.
Calliphora vomitoria, 155, 188. Orthoptera, 159.
Caloptenus, 160. Petrophora, 164, 171.
Ceuthophilus, 159, 162. Phryganea grandis, 189,
Chauliognathus Pensylvanicus, 170. Phryganeidae, 184.
Chironomus, 180, 186. Phytonomus punctatus, 172, 173.
Cicada septendecem, 190. Pieris, 172, 174.
Coleoptera, 170, 172, 190. Ptilodactyla serricollis, 164.
Colias philodice, 172, 174. Pyrrharctia isabella, 160.
Coriseae, 177. Sapromyza, 188.
Culex, 158, 163. S. longipennis, 180.
Culicidae, 172. Simulium molestum, 158.
Deltoid moth, 164. S. latipes, 189.
Diptera, 155, 158, 159, 163, 164, 166, 167, 172, 180, 181. Spilosoma virginica, 159.
Eupithecia, 171. Syrphidae, 155, 188.
Flies, 155, 158, 164, 179, 188. Syrphus, 156.
Guats, 158, 164, 166, 185, 186. Tenthredo, 162.
Grasshoppers, 159, 188. Thera, 171.
Halictus, 172. Thripidae, 172.
Hemiptera, 164, 165, 168, 169, 171, 175, Thrips, 172, 174.
Hyphantria textor, 159, 160, 164, 165. Tipulidae, 159, 172, 181.
Hymenoptera, 162, 172. Tipula, 161, 163, 167, 177, 188.
Ichneumonidae, 172. Tortrix, 164.
Jassus 6-notatus, 187. Typhlocyba (mali et rosae), 164, 172, 173.

Lampyridae, 170, 172.

ERRATA,

Page 142, line 11 and p. 143, line 6; for apiculatus read apiculata,
Page 153, line 11, after conica insert radicans.

201

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Plate XI
BMeizel

10-16. CULICIS. 17-48. GRYLLI.

1-9.MUSCE.

Memoirs Boston Soc Nat Hist. Vol. IV
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Memoirs Boston Soc. Nat Hist. Vol. IV Plate XV

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Memoirs Boston Soc.Nat Hist. Vol. IV Plate XVI

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91-105. CAROLINIANA. 106-140. FRESENII. 141-160. LAGENIFORMIS.

Memoirs Boston Soc.Nat Hist. Vol. IV Plate XVI

-RThaxter,del.ad nat, BMeisel. liu

161-172. LAMPYRIDARUM. 173-178. GEQMETRALIS. 179-199. OCCIDENTALIS.
200-219. SPHA.ROSPERMA.

Memoirs Baston Soc. Nat Hist. Vol. lV Plate XVI!

ReThaxter,del ad nat B Meisel. lith.
220-240. APHIDIS. 241-250. DIPTERIGENA. 251-261. VIRESCENS.
262-273 AMERICANA 274-285. MONTANA.

Memoirs Boston Soc.Nat Hist. Vol. IV Plate XIX

Re AU PD
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{hy AT] Z,
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326

RThaxter, del ad nat. : B Meisel, lith

286-305. ECHINOSPORA. 306-326. SEPULCHRALIS.

Memoirs Boston Soc.Nat Hist. Vol. IV

378

B Meisel, lith

RThaxter, del ad nat.

347-378. RHIZOSPORA.

327-346. VARIABILIS.

Plate XXI.

Memoirs Boston Soc. Nat Hist. Vol. IV

B Meisel, lith

4\0-413. RANARUM.

392-409. CONICA.
414-429. CICADINA.

379-391.GRACILIS.

Blea t pean ei Pa ae
De Oe . oe

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