•x^ \ -'1 1^ THE RELATION BET'.TEEN BllAIlI V/EIGHT AlTD THE TIIvIE KEQ,UIRED FOR HABIT FORIM-TION IH THE ALBIIIO RAT. A DISSERTATION SUBMITTED TO THE BOARD OF UNIVERSITY STUDIES OP THE JOHNS HOPKINS UN INTERS ITY IN CONFORMITY WITH THE REQUIREJlIENTS FOR T.HE DEGREE OF DOCTOR OF PHILOSOPHY BY G.\RDNER CHEITOY BASSET. I u ^11 ACKROY/LEBGIffiNTS. Before entering upon the body of this presentation I desire to express rny obligations to thoHe v/ithout v/hose co- operation ny experinents would have been of less value. Above all r^rr. I indebted to Professor John E. \7atson, Pirector of the Johns Hopkins Psychologicc.! Laboratory, who has kept himself informed of the progress of my experimenta- tion and who has been ready at all times with helpful suggest- ions and encouragement. To Dr. Henry H. Ponaldson I owe much: for suggest- ing the experiment; for placing the facilities and material of the V.'istar Institute at my disposal; for much helpful ad- vice as to the evaluation of my results. To Dr. Shinkishi Hatai for preparing the anatomical data referring to the rats used in my experiments. To Dr. Helen D. King for keeping her sequences of inbreeding moving so perfectly that, at any time, I was able to procure inbred rats of the desired age. Gardner Cheney Easset. CONTENTS, I. Introduction. II. Methods. III. Experiment 1: the l-'ay^e. IV. Experiment 2: the Preliminary Inclined Plane, V. Experiment 3: the Inclined Plane, VI. Bunmary and Conclusions. I. ii:tkouuctioii. A few years ogo experimenttil inbreeding of the al- bino rat, L'us norvegicus albinus, was started at the V/istar Institute of Anatomy and Biology in order to determine the anatomical consequences of such procedure upon successive gen- eration? of progeny, /unong other results obtained was a dis- tinct and progressive decrease in actual and relative brain weight (relative, that is, in reference to body length) for four generations of close inbreeding. From the fourth to the tenth generations the relative brain v/eight remained, on the average, constant at six and one half percent less than that of the average normal rat. Vfhen, early in October, 1911, V)t, Donaldson suggest- ed to Professor \7atson that the deterioration in brain weight might be accompanied by a similar deterioration in the abili- ty to form habits a nev,- line of investigation in comparative psychology was opened up. The problem was offered to the v/rit- er and gladly accepted. In regard to the question as to whether inbreeding, per se, has deteriorating effects upon progeny it is unsafe to be arbitrary, and authoritative testimony must await the results of further investigations. ^7e know, upon the author- ity of historii^ns, that the Incas of Peru for many generations married their oldest sisters and were, until their extinction by the Spaniards, physically and mentally superior to their subjects. Breeders of domestic animals frequently resort to inbreeding in order to perfect desirable qualities in the strain. It may be, as many claim, that inbreeding io deteriorating only in cases where an hereditary taint, appearing, in the com- mon ancestor, is strengthened in the progeny of a conscinguin- eou8 union. Of the rats used in tlie experiments hereinafter described it is not postu.ltited tliat the lesser ability to foi'in habits is necessarily due to inbreeding; but the rats used for purposes of inbreeding produced a strain having a lesser relative brain weigiit, which rats, for convenience, I shall hereafter refer to as the Inbred strain. The object, then, of the folloving experiments is to compare the habit-forming ability of tl:ie inbred strain with lesser brain v/eirhts v/ith the ability of a normal control series. Owing to the fact that experimental v/ork on tlie brain weight problem has net before been attempted there is no his- tory and little literature to be presented. Donaldson-^ repro- duces tables from Ilanouvrier''- showing the brain weights of eminent men to be, on the aTerage, greater than those of av- erage Parisians. It is not necessarily true that the specific individual ^vith greater brain weight is more intelligent or v.'ill contribute more to the v/orld's arts and sciences than the specific individual of lesser brain weight, but, if the tables of jVanouvrier axe to be believed, individuals . of great- er brain v/eight are more likely to be more intelligent and to do the world greater service. •^Lonaldson, The Growth of the Brain, London find I'ew York, 1909, pp. ]2e ff, 2 Manouvrier, Sur 1 ' interpretation de la quantity dans 1 'Enc*- phale, Lc, PariH, 1865. The results of the experiments hereinafter describ- ed agree closely with llanouvrier 'b tables. Tablep of distri- bution of brain weights of the inbred strain and bormal con- trol series overlap; but the normal sei-ies, having a greater brain weight average, show greater ability in habit formation. Al!) the experiments here described v/ere carrieB out at the Psychological Laboratory of the Johns ^lopklns Univer- sity. II. I^OSTHODS. All the inbred rata used in thif=i investigation were bred at the Wistar Institute by Dr. Helen D. King. Two strains were used, referred to in this paper' as strains A and B, The original parents of each strain v/ere picked at random, a male and female from each of two unrelated litters. The A male v/as mated to his sister, A female, and the B male to his sister. Their respective litters constituted, generation lA and IB. From this point inbreeding v/as carried on by selecting from the litter the healthiest appearing rats and mating brother to sister v;ithin the same litter, this constituting the clos- est possible inbreeding. At about thirty days of age the young rats were taken from their mother and those to be used by the writer were shipped to the Johns Plopkins University. There were no fatalities en route, and all arrived apparently in good condition. The system of numbering individual rats as a.ppears in the tables is as follows: the first nunberi refers to the generation of inbreeding, the letter to the strHin (A or E) and the last number identifies the individual. 7or ex- ample 7A909 is analyzed as follows: 7th generation inbred, A strain, individual 90, female. It seemed advisable to secure normal control muting strains from different laboratories in order, to avoid any pos- sibility of inbreeding. Control strain H is from the Johns Hopkins Laboratory, W from the stock rats of the V.'iatar Insti- tute, C from Columbia University, B a litter bought from a Baltimore dealer, and E a lart,e male given to me by Ir. Her- bert L'. Fvans of the Johns Hopkins I.'edioal School. Care was taken in mating the control series to avoid any approach to inbreedinti. As in the case of inbred rats the youn^ v/err tak- en fron the niother at the ajc of thirty daye. The oysten of nunbering individual normal rata as appears in the tables in 38 follows: the first letter, S, signifies that it is a stan- dard or normal control rat, the letters within the parenthe- sis {^ive the pedigree and the figures give the indivicual num- ber. For example, S(C/EE)70d' is analyzed as follows: standard or normal control series, C father, E maternal grandfather, B maternal grandmother, individual 70, male. ^\Tien taken from the mother the males v/ere kept in ca^es separate from the females. In order to keep conditions constant neither males nor females were allowed to mate. As solitude may affect behavior, from three to five rats were kept in each cage. The cages were sufficiently large (24"xl5" xl5") to permit this. Cages were frequently disinfected with a preparation, Creso Dip, the principal Ingredient of which is carbolic acid. A layer of clean chips and shavings was kept on the floor. The food, from date of weaning, consisted of bread soaked in milk (no water), and, tv/ice a week, grain and sunflower seeds. Temperature was kept as uniformly as possible at 70°r. In order to facilitate this a small gas heater was instPdled and it proved very efficient durin^^ the coldest days of winter. As the animal laboratory is located in the basement the temperature, during the sursmer-, rarely rose above cur norm. At the age of sixty days the rats intended for ex- perimental purposes were placed on a short allowance of feed- int time (thirty minutes) in order to prepare them for experi- mentation. The experiments were begun uniformly at the age of seventy days. Care was taken in each experiment to use the same number of males and females in the control series as in the inbred; this was necessary because, as in nan, the relat- ive brain weight of the f ena] e ia greater tljan that of the male. Fxperimente upon individual rata v/ere conducted as near- ly as possible at the sane time of day, thus fornin^-, feeding rhythms. There are three methods of estimotinti perfection in experiments relatin^i to the behavior of animals; the num- ber of erroi's, the distance traversed and the time required. In any case it is hard to form a judtgrnent as to what consti- tutes an error and especially so in a comparative study of this kind where it is possible for the personal prejudice of the experimenter to enter. At the time this investigation v/as begun there was no adequate means for measurint? the distance traversed. This left the time consumed as the only criterion of perfection. However, time is the criterion used by most investigators in the animal field. Hicks^, in summing up the experimental results of several investigators concludes, that "time is the best single criterion, inasmuch a,s it represents all phases of the process of lefnrning, and since it will yield the most, comparable results at the hands of different inves- tigators." In timing the rats a very accurate Sv/iss split-sec- ond 8top-v,'a,tch was used. Under ideal conditions, perhaps, the animal should be presented to the problem by one person, tim- ed by another, while the experimenter himself should merely record results. But timing very soon becomes automatic; when the rat is crossing the starting line it is almost impossible to inhibit the impulse to press the button. Hicks, The Relative Values of the Different Curves of Learn- ing, Jl. of An. ^eh., vol. I, pp. 138 ff. At the conclusion of the experimentn all the rwts V used were shijjped to the Wistur Institute, where Lr. Shinki- shi Hatai ascertnined the body lerij^th and weight, bruin and cord weight, and the ^ercente-ce of water in brf>in and cord. From the figures supplied by him I was enabled to draw up the anatomic?! data and to formulate the relations between rela- tive brain weight and habit formation. III. KXPSHIIOTTT 1: TIffi lilAZE. The apparatus used in thiB experiment was the Wat- son liaze (Plate l). This n;ir,e if» circular in forn, five feet in dijijneter, witji entrancea from outer runways to the next inner at alterjiiate ends of a quo.drant arc. The partitions are of aluninun and rise to a heij^ht of five inchen above the floor of the maze. A heavy wire screen resting on top nerves the purpose of preventing the rats from climbing over the parti- tions, and also allovs the experimenter to observe all move- ments within. The perfect course of the aninal running is, from the entrance, E, through runway entrances 1, 2, 3, 4, 5, 6 and 7 to F (food). Each side of runv/ay entrances 2 to 6 inclusive lead into cul-de-sacs. The object of the experiment was to have each rat learn to reach the centre, F, in the least possible time, the starting time being taken when the animal crossed runway en- trance 1, and the finishing time when he crossed entrance 7. In preparation, each animal, beginning at the a/re of sixty-five days, was fed alone in the centre, F, for ten minutes daily for five consecutive days. During this period the centre was barred from the rest of tVie maze at entrance 6. At the age of seventy days the experiment began. Eleven males and ten females from the inbred strain were used and, as control, an equal number of males and females from the nor- -al series. Of the inbred rats, foutteen were from the 6th j.en- cration and seven from the 7th. The stimulus used was the food to which they had becoiae accustoiaed, bread soaked in milK. f^ach rat was reouired to run from E to ? five times each day. At the end of the fifth trial it was allowea to feed in ? for five lainutes, but perraitted no more food until, the completion of the next dny ' a experlinent . Each i^ft.t was used daily until it had learned the course perfectly, the criterion of perfection beint; five perfect trials for each of three suc- cessive days. A perfect trial consisted in runnin^j the course within six seconds, a period so short that it was practical- ly impossihle for the rat to make p detectable error p.nd reach the centre v;ithin that tine. Those rats failin^; to learn v-'ith- in one hundred days (500 trials) were no longer used for ex- perimentation. Those rats learning the mase were, at the con- clusion of the experiment, fed for sixty days in a rvinv/ay tven- ty-five feet long with a feeding box at the far end. At the end of this period they were tested for retention and relearn- ing. The results of the experiment for the inbred rats are given in tables la, lb, and Ic; for the normal control series in tables Ila, lib, and lie. These tables give only the averages of the five daily trials of individual rats. The shortest period of learning for an inbred rat was twelve days; for a normal control, ten days. Two inbred rats and one nor- raal failed to learn the maze at all. This paper does not pre- tend to take up individual differences, but certain of the normal control series showed peculiarities of behavior simi- lar to those of the inbred series. These peculiarities, for the most part, consisted in disorientation and persistent er- rors. Strain B of the control series exhibited these peculiar- itif^a to such an extent and were so slow in learning (the con- trol rat failing to learn at all was from this strain) that the investigator suspected this strain to be of lesser rela- tive brain weight; and, when the returns were received from the V/istar Institute, this was indeed found to be the case. 10 Tables la and Ila shov/, vesxjectively , the aaily a,v- erai^e time in seconils of the inbred and normal control series durinej the process of formation of the naze habit, Aft^r the standard set for perfection (five perfect trials of six sec- onds or less each, for each of three consecutive dayg) htid been reac'ied, t]ie average time of the three perfect days was carried on for the succeeding days in red ink. For example, in Table la, the ti>ie record of rat 6B10?c? is recorded thus; day 10, 5.12 seconds; day 11, 4.92 seconds; day 12, 5.04 sec- onds. The average of these three perfect days, 5.03 seconds, is carried forward in red ink. It is necesgary to preserve these figures in order to compute the total daily averat;es based upon which the curves of learning; are constructed. Table lib, the daily averas^es of the control series, is especially significant showing, as it does, the erratic behavior of the B strain. By the end of the twenty-fourth day all the normal group had formed the perfect raar.e habit with the exception of five rats from the 3 strain; nor did any of these five become perfect until a week later v/hen two dropped out. One B rat persisted in the same error, pas3in<^ entrance 2 into the cul-de-sac at the right, with occasional other er- rors and did not learn the problem in the hundred days allow- ed. Tables lb and lib show what I have termed the abso- lute retention of, respectively, the inbred and normal control series. Absolute retention is -aeasured by the time required to complete the first trial of the relearninj^; series after the sixty days' rest; the stronger the retention, the less the time. These tables show the absolute retention of the nor- mal control series to be much stronger than that of the inbred, Tables Ic and lie show, respectively, the daily av- J.i erage time in seconds of the inbred and normy] control nerlea during the process of relearning. The two inbred and one con- trol rat failing; to lenrn the maze ^'/ere not, of course, test- ed for relearninti. Of those inVjreda so tested, two had fail- ed to relearn within fifty days, in consequence of which it was thou^iht uselesa to carry theia further. aII the control series had relearned at the end of twenty- two days. Tables Id and lid show, respectively, the anatoi.iic- al data of the inbred and norraal control rats used in the naze experiments, based upon figures sent by the v/istar Institute. These tables will be treated fully in the conparative su/oina- ries. For j^reater convenience in making a comparative stu- dy I have placed together in Table III a summary consisting of the daily avera^^^es of all the inbred a.nd all the control rats. From this table, too, are constructed the conparative curves of learning/. The table shows that two of the inbred and one of the norraal rats failed to i'earn the maze habit. The inbreds required, on the average, 36.62+day8 to learn; the normals but 24.67+, The absolute retention of the inbreds was, on the ayeni^e, 81.558 seconds; of tne normals, 59.640 seconds. Two of the inbreds failed to relearn; all the normals had relearned at the end of twenty-two days. The inbreds re- quired, on the average, 12.68-rday3 to relearn; the normals but 5.75. In all these criteria of ability the rats of the norma.] control series are shown, on the aver.^tl^j to be super- ior to those of the inbred series. There are two possible criteria for estimating the relative brain weight -- in reference to body length and in reference to body weight. In a healthy normal rat the differ- ence between uody \veit,ht in {_rara8 -md body len^t>i in lai] 1. ime- tres is slij/ht. But under conditions of ovei^feedint^ or of sic'K- ness the body weight varies j^reatly while the bociy lent^th re- mains constant. "For this reason Pr. JJonaldson has accepted body lent^th as the sole criterion. In these tables, however, both nre produced. Eoth body Icn^jth and body v;eit:ht of the inbred rats used in the nane are, on the avera^-e, a trifle greater than is the case with the noriaals. The avera^ie actual brain weight of the inbreds is less than that of the normals. The relative brain weight (in reference to body length) of the inbreds is 4,43;1 less than that of the normals. The rela- tive brain weight (in reference to body weight) of the inbreds is 1.99% less than that of the normals. The percentage of wa- ter in brain and cord decreases v/ith age, but in the inbreds of the maze series, although killed on the aTerage fourteen days later than the normals, the percentage of water was great- er. The tables of comparative surru.iaries of mar>e results support the hypothesis that the deterioration of brain weight in a strain of rats is accompanied by deterioration in the ability to form habits. In Plate II is shown the curve of learning (below) and of relearning (above) of the inbred rats compared with those of the normal control. The inbred curve is shown by the solid line, that of the control by the broken line. The ordi- nates give the average time in seconds, and the abscissae the number of the day in which such time was made. The time requir- ed by both inbreds and normals for the first four days w.-.s 80 long that it is represented here by fig\jrea rather tzian by the curve. For the first few days the descent in both cas- es is very rapid, and from the twentieth day the normal curve lies entirely below the six necond mark. The inbred curve nev- er rcach.ea a flattened appearajicc but shows ^^reat irretjular- itiea, particularly on the forty-fifth, sixty-firat, ei^jhty- second, ninetieth and ninety-second days. The inbred curve of relearning is more similar to that of the control, but it must be borne in ;iind that the tv/o inbreds and one normal fail- ing to learn are not represented here. From the tv/enty-second day the normal control curve is perfectly flat at 5.3 seconds, all the animals having relearned. Two of the inbreds failing to relearn, their c\irve of relearning remains slightly irreg- ular and above that of the normals. In Plate III nay be seen the distribution curves of learning and relearning of both the inbred and control ser- ies for the maze experiment. The time is given in days -- in groups of five for learning, in groups of two for relearning. As may readily be seen, the advantage from the standpoint of time (days required to learn and relearn) lies wholly in fav- or of the normal control series. The question arises as to whether the later genera- tions of inbred rats differ from the earlier in the ability to form habits; that is, is deterioration in this ability pro- gressive, even if, as earlier stated, deterioration in relat- ive brain weight after the 4t}'i generation is not. Of the in- bred rats used in the maze, fourteen were from the 6th genera- tion and seven from the 7th generation. In Taole IV is shown a comparative summary consisting of the daily averages of all the 6th and all the 7th generations. From this table, too, are constructed the curves of learning of the 6th and 7th gen- eration inbreds. The table shows that two of the 7th genera- tion failed to learn the maze; all the 6th generation had learn- ed it at the end of eit^hty- three days. The 6th generation re- J quired, on the Hveratje, 32.93 days to le.-irn; the 7th jener;*- tion, 44.00/. The absolute retention of the 6th tieneration was, on the :a.veraije, 65.443 seconds; of the 7th tbcneration, 126.680 seconds. Two of the 6th generation failea to i-eleiirn; all the 7th generation had relearned at the end of fourteen days. The 6th tjeneration required, on the average, 14.14 ( days to r el earn; the 7 th ^^eneration but 8.60. In these criteria of ability, the 6th (ieneration excelled in learningi and absolute retention; the 7th in relearn- ing. It nust be renenbered, however, that two rats of the 7th generation, having failed to learn, were not tested for relearn- ing. On the whole, the ability of the 7th generation inbreds in learning the naze appears to be soi.iewhat inferior to that of the 6th. The body length and body weight of the 6th genera- tion average greater than those of tne 7th. The averat^e actual brain weight of the 6th generation is greater than that of the 7th. The relative brain weight (in reference to body length) of the 6th generation is .91^^ less than that of the 7th gen- eration. The relative brain weight (in reference to body weight) of the 6th generation is 1.50/" less than that of the 7th gen- eration. The relative brain weight of the inbred rats used in the maze has not deteriorated fron one generation to anoth- er; however, the number of rats considered in each generation is but few, and all from the 7th generation are females hav- ing greater relative brain weights than males. The percentage of water in brain n.nd cord is within .03;:^ of the 3:une figure in the two generations. In Plate IV is shown the curve of learning (below) and of relearning (above) of the 6th and 7th generations of inbred rats. The 6th generation curve is aiiown oy the broken J.CJ line; that of the 7th tjeneration by the solid line. The ordi- nates t^ive the time in seconds, and the absciBane the nuinber of the day in which such time was made. From tlie twenty-second day in the curve of leai'ning the 6th generation curve is be- low the second mark, and from the eighty- third day is flat at 5.158 seconds. The 7th tieneration learninti' curve is very ir- regular throughout its length and never approaches the appear- ance of learning. The 7tia generation relearning curve, howev- er, is slightly better than the 6th, being flat from the 14th day at 5.656 seconds; but the two rats that failed to learn are not represented in this curve. The siinilarity in behavior of the rats of the con- trol series containing 3 blood to that of the inbreds has al- ready been mentioned. Table V presents a summary consisting of the daily averages of the nine control rats containing B blood and the twelve control rats lacking it. Eight of the rats containing B are l/2 C and l/2 B; the other is 1/2 C, 1/4 F and l/4 B. l^Iost of the rats lacking B blood contain C, which makes void the possibility that C is a factor in the lack of ability in the strain containing B. In order to com- pare the behavior of control rats having B and those lacking it vvith the inbreds, cross references may be made from Table V to the inbred averae:,e3 of Table III. The control rats having B blood shall be referred to as B rats; those lacking B blood as (-B) normals. The tubles shov/ that two of the inbreas and one of the 3 failed to learn the naze; the ( -B ) norm-ils had all learn- ed at the end of the twenty-fifth day. The inbreds required, on the average, 7)6. 62^- days to learn; the B .35.67^ ; and the (-3) but 16.42. The absolute retention of the inbreds was, on the average, 81.556 seconds; of the 3, 72.475 seconds; and of the (-13), but 51,083 seconds. Two of the inbreds fuiTed to relearn; all the B haa relearncd at the end of the twenty-sec- ond day; while all the ( -L ) had rel earned at the end of the eighth day. The inbreda required, on the average, 12.68- days to relearn; the B, 8.24 days; the (-E), but 4.08 days. In these criteria of ability the inhreds did the lepst well; the 3 rnts were, in each instance, not far from their record; the (-3) were nuch superior to either. 3oth body lentith and body weight were e^reatest in the inbreds, next in the B, and least in the (-B). Actual brain weight was lenst in the inbreds, much greater in the 3, and slightly greater in the (-3) than in the 3. The relative brain weii:ht (in reference to body length) of the inbreds *as 5.46;^ less than that of the (-5); that of the 3 was 2.53^^ less than that of the (-3). The relative brain weight (in reference to body v/eight) of the inbreds was 10. 02,^ less than that of the (-3); that of the 3 was 5.15> less than that of the (-3). As might be expectea from the behavior and the hypothesis, the average relative brain weight of the 3 strain lies between that of the inbreds end of the (-3). The results here obtained reinforce the former con- clusion that deterioration of brain v/eight in a strain of rats is accompanied to a similar degree by deterioration in the ability to form habits. In Plate V is shovm the curve of learning (belov/) and of relearning (above) of the inbred -ind 3 rats compared with those of the (-3). The inured curve is represented by the solid line, the 3 by the heavy broken, and the (-3) by the lighter broken line. The oruinates ^^ive the average time in seconds, and the abscissae the nuiiber of the day in whicli such time was made. From the tv/entieth aay the (-3) curve is flat Pt 4.9 seconds. Heither the inbred nor the B curvea flat- ten entirely, althou^''^ the B oirve is more rejjular than that of the inbred3. The curve of relearnintj (without the two in- breds and one B that failed to learn) of all three nearly co- incides. But here the inbred rernains slit^htly above, and the (-B) slightly below the curve of the B. Rat # Day 1 Day 2 Day 3 Day 4 Day 5 eA7icr 287.60 33.60 13.96 11.84 9.]2 6A72cf 570.20 19.52 15.72 11.52 7.60 6A73cf 524 . ] 2 34.92 15.32 12.52 10.28 6B70d 853.16 86.08 90.68 - 66.68 58.32 6I371cr 940.96 120.76 81.56 32.80 30.44 6B72<:f 553.84 97.48 65.36 41. ]2 31.76 6B730" 217.40 53.12 72.96 67.12 35.72 6B101c^ 375.24 105.04 105.56 83.40 64.76 6B102cr 453.16 158.92 464.44 55.20 91.12 6B103cf 173.24 57.24 52.72 45.84 14.00 6B104d' 661.60 43.76 14.72 7.32 11.40 6E769 1556.44 77.20 48.40 39.28 32.36 6B779 280.60 118.20 58.40 31.00 16. ]6 631069 132.36 20.96 20.16 18.64 7.]6 7A259 451.04 151.24 31.68 20.40 14.04 7A269 761.84 260.76 127.36 73.04 27.36 7A559 151.64 29.80 24.56 90.56 18.80 7A569 1451.24 369.20 92.00 97.48 36.28 7A579 467.56 15.56 10.52 9.28 8.20 7A899 155.96 45.44 8.56 5.92 4.68 7A909 145.76 20.68 16.72 7.68 5.36 Average 531.665 91.404 68.360 39.459 25.568 ible la. Haze Learning by Inbred Rats. jLy Rat # Lay 6 Day 7 Lay 8 Lay 9 Lay 10 6A71cf 7.76 11.84 8.32 8.80 7.44 6A72cf 10.88 11.96 10.28 8.92 6.92 6A73cf 23.44 13.72 10.72 12.00 10.84 6B70d' 26.88 12.72 9.32 6.40 6.96 6B71d' 15.04 15.20 8.24 6.88 10.28 6B72cf 14.60 13.36 9.44 8.92 6.52 6B73d' 21.04 18.44 11.92 10.44 10.20 6B101cf 105.44 54,48 17.] 2 17.08 11.56 65102^ 32.64 27.48 18.92 14.92 13.28 6B103d' 8.76 7.96 6.76 6.76 5.32 6B104cf 7.64 4.84 8.16 4.68 4.56 6B76$ 17.92 14.16 14.44 17.60 19.32 6B77$ 10.80 9.32 8.56 7.84 16.64 6B106$ 39 . 36 13.72 6.84 15.56 7.40 7A25$ 8.84 7.84 7.64 8.64 7.04 7A269 20.40 14.04 15.04 9.24 8.04 7A559 8.S6 7 . 52 6 . 52 5.36 5.88 7A56$ 20.00 17.84 15.00 15.52 19.68 7A57$ 5.80 5.]2 6.32 5.40 5.76 7A599 5.36 5.04 16.60 4.48 10. ]2 7A90$ 8.96 5.28 16.32 8.44 6.40 Average 20.015 13.899 11.061 9.709 9.522 Table la. Kaze Learning by Inbred Rats, 20 Rat j'f Day 11 Day 12 Lay 13 Day 14 Day It; 6A71cf 8.36 8.92 6.88 6.76 6.80 6A72d' 7.D2 8.32 7 . 32 7.56 7.48 SAlid 8.72 8.76 9.60 9.60 8.76 6B70cf 7.52 7.04 5.04 6.72 5.76 6B71cr 5.76 5.36 5.24 7.92 6.80 6B72d'' 7.28 6.64 o.OO 6.52 6.44 68730? 11.80 8.32 7.96 9.76 7.48 6B101O' 13.28 16.56 14.44 10.24 12.32 eBlOScT 12.00 b.92 7.96 7.32 6.28 6B103cf 4.92 5.04 5.03 0.03 5.03 6B104d' 9.72 5.08 6.32 5.00 4.76 6B769 44.60 10.20 12.16 15.40 11.08 6B77$ 8.32 12.12 36.68 8.68 6.04 6B108$ 6.60 4.84 4.92 4.60 4.79 7A25$ 7.80 6.20 6.88 6.92 6.36 7A269 13.76 7.96 8.56 9.72 7.96 7A559 5.88 4.80 4.76 4.68 4. '75 7A56$ 12.92 13.20 9.08 7.44 12.08 7A579 8.12 6.52 5.88 6.36 4.84 7A699 0.36 6.60 7.00 5.04 4.80 7A909 4.92 5.28 5.16 8.32 6.40 Average 10.217 7.937 6.708 7.600 7.000 'able la. lAaze Learning by Inbred Rats. 2: Eat ^i Day 16 tay 17 Day 18 Day 19 Day 20 6A71cf 6.64 6.04 5.52 6.56 6.48 6A72cf 7.08 6.04 6.]6 6.04 5.52 6A73cr 7.96 7.00 7.68 7.88 9.20 6E70cf 5.44 6.08 5.88 6.92 7.00 eB?!^ 5.24 4.92 4.88 5.92 6.44 6B72cf 8.84 5.48 10.32 7.96 5.40 6B73cf 5.84 7.48 5.64 5.60 6.08 6B101C? 10. ]2 8.88 9.96 7.56 7.60 6B102C? 6.28 5.88 6.00 6.48 5.76 6B103d' b.O? 5.03 0.03 5.03 5.03 6B104d' 5.00 4.52 4.76 4.76 4.76 6B76$ 10.28 10.96 6.32 7.40 6.32 6B779 6.20 9.56 5.96 6.36 7.52 6B106$ 4.79 4.79 4.79 4.79 4.79 7A259 5.96 6.96 5.92 7.96 7.48 7A26$ 6.88 9.52 8.56 9.08 12.88 7A559 4.75 4.75 4 . '^5 4.'>5 4.75 7A569 7.84 8.20 7.68 9.36 6.36 7A579 4.64 4.68 4.72 4.72 4.72 7A699 4.68 4.84 4.64 4.84 4.14 7A909 5.72 5.68 7.04 6.36 4.88 Average 6.439 6.585 6.305 6.492 6.458 Table la. I'aze Learning by Inbrec Kats. Rat # Lay 21 Day 22 Day 23 Day 24 Day 25 6A71cf 7.44 !).28 6.52 6.76 8.84 6A72d' 6.24 7.04 5.32 6.86 6.04 6A73d' 8.72 6.68 9.00 6.80 6.96 6B70c^ 5.28 5.08 4.56 - 4.97 4.97 6B71cr 6.00 5.24 5.72 5.88 4.92 6B72cf 7.56 5.J2 5.52 4.96 5.48 6B73cf 5.08 4.80 5.72 4.72 5.36 6E101d' 9.20 6.16 9.44 6.72 6.44 6E102cf 7.52 6.56 6.32 5.66 6.12 6B103cf 0.03 5.03 5.03 b.03 5.03 6B104d' 4.76 4.76 4.76 4.-76 4.76 6S769 5.24 5.44 5.12 5.00 5.19 6B779 5.00 5.40 4.96 5.12 7.16 6BIO69 4. ''9 4.79 4.79 4.79 4.-79 7A25$ 9.96 5.68 6.20 6.20 5.64 7A269 7.84 6.60 8.88 10.16 8.96 7A559 4.75 4.75 4.75 4.75 4.75 7A569 8.64 8.88 8.64 7.16 13.32 7A579 4.72 4.72 4.72 4.72 4.72 7A699 4,84 4.84 4.84 4.84 4.84 7A909 5.00 4.88 4.92 4.92 4.92 Average 6.362 5.749 5.978 5.753 6.848 Table la. Haze Learning ty Inbred Rata. 2?> Rat # Day 26 Tay 27 I^ay 28 Day 29 Day 30 6A71d' 7.96 8.04 5.88 6.52 5.60 6A72d' 6.32 6.76 5.20 6.16 5.28 6A73cf 6.eo 7.00 6.36 6.40 6.96 6B70d' ^.97 4.97 4.97 - 4.97 4.97 6B71d' 4.88 4.92 4.91 4.91 4.91 6B72cr 4.88 5.32 5.20 5.36 4.96 6B73d' 5.36 4.88 4.80 5.52 5.32 6B101C? 6.48 7.92 6.64 6.64 7.64 6B102d' 6.]6 5.56 5.60 5.32 6.32 6B103cf 5,03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B769 5.39 5.19 5.39 5.39 5.19 6B77$ 5.08 4.88 5.04 b.OO 5.00 6B108$ 4.79 4.79 4.79 4.79 4.79 7A259 5.88 6.88 6.52 9.40 6.28 7A26$ 7.64 7.72 6.52 11.00 7.Z2 7A559 4.75 4.75 4.75 4.75 4.75 7A56$ 9.20 35.88 10.40 18.32 9.88 7A579 4.72 4.72 4.72 4.72 4.72 7A699 4.84 4.84 4.84 4.84 4.84 7A90$ 4.92 4.92 4.92 4.92 4.92 Average 5.734 7.3 30 5.669 6.387 5.697 Table la. Maze Learning by Inbred Rats. Rat f^ ray 31 Day 32 Lay 33 Tay 34 Day 35 eA71d' r. . 04 6.32 7.04 r).44 5.28 6A72cr 6.04 6.40 6.20 5.92 6.68 6A73d' 6.76 9.36 7.24 9.60 6.36 6B70cr 4.97 4.97 4.97 - 4.97 4.97 6B71cr 4.91 4.91 4.93 4.91 4.91 6B72d' 5.11 5.11 5.11 5.11 5.11 6B73c^ 4.68 4.76 4.60 4.68 4.68 eBioid- 5.84 7.48 8.08 7.44 6.36 6B102CJ' 5.36 5.36 5.40 0.37 5.37 eBiostf 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B769 5.19 5.19 5.19 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 6Bioe$ 4.79 4.79 4.79 4.79 4.79 7A25$ 6.08 6.32 6.04 12.12 5.52 7A269 6.00 6.92 6.48 7.52 6.40 7A55$ 4.75 4.75 4.75 4.75 4.75 7A569 7.28 7.96 9.68 9.68 12.72 7A579 -.72 4.72 4.72 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4.84 7A90$ 4.92 4.92 4.92 4.92 4.92 Average 5.384 5.708 5.702 6.084 5.731 Table la. Llaze Learning by Inbred Rata. Rat if Day 36 Lay ?7 Day ."58 Day 39 Day 4 0 tklld' 5.48 5.48 ,,.4J U.sl 'o.Al ekizd 7.04 6.56 5.84 5.66 5.76 6A73C? 6.64 7.48 6.60 6 . 24 5.88 SEVOcf 4.97 4.97 4.97 - 4.97 4.97 6B71cr 4.91 4.91 4.91 4.91 4.91 6B72cf b.]l 5.11 5.11 5.11 5.11 6B73cr 4.68 4.68 4.68 4.68 4.68 esioicT 6.72 6.88 6.32 7.28 6.44 eBioad" 5.37 5.37 5.37 5.37 5.37 6B103d- 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B76$ 5.19 5.19 5.19 5.19 5.19 6B779 5.00 5.00 5.00 5.00 5.00 6BIO89 4.79 4.79 4.79 4.79 4.79 7A259 6.32 5.32 5.64 5.36 5.44 7A265 8.36 6.28 6.64 7.00 14.92 7A559 4.75 4.7^ 4.75 4.75 4.75 7A569 8.00 7.96 9.88 10.32 9.92 7A579 4.72 4.72 4.72 4.72 4.72 7A89$ 4.84 4.84 4.84 4.84 4.84 7A909 4.92 4.92 4.92 4.92 4.92 Average 5.590 5.476 5.^194 5.540 5.848 Table la. Ilaze Learning by Inbred Rats. .?6 Rat # Day 41 Day 42 Lay 4 3 Lay 44 lay 4 5 eA7icr J. 41 5.41 5.41 5.41 5.41 6A72cf 5.76 5.76 5. '76 5.76 i..76 6A73cr 7.24 8.28 6.68 6 . 52 7.08 6B70cf 4,97 4.97 4.97 - 4.97 4.97 6B71d' 4.91 4.91 4.91 4.91 4.91 6B72C? 5.11 5.11 5.11 5.11 5.11 6B73cf ■1.68 4.68 4.68 4.68 4.66 ' eBlOld" 7.36 12.68 7.88 6.16 8.40 6B102cf 5.37 5.37 5.37 5.37 5.37 eBlOSd" 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B769 5.J9 5.19 5.29 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 63IO89 4.79 4.79 4.79 4.79 4.79 7A259 5.44 5.44 5.44 0.44 5.44 7A269 10.00 8.52 7.92 9.04 172.12 7A559 4.75 4.75 4.75 4.75 4.75 7A569 8.20 10.40 10.12 8.68 9.32 7A57$ 4.72 4.72 4.72 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4.84 7A909 4.92 4.92 4.92 4 . 92 ■1.92 Average 5.640 5.978 5.631 5.526 13.456 Table la. Ha'/.e Learning by Inbred Rate. 27 Rat # Day 46 Day 47 Day 48 Day 49 Day 50 6A710' 5.41 0.41 5.41 0.41 5.41 6A72d' 5.76 b.76 0.76 0.76 0.76 6A73cr 7.84 6.96 7.76 7.68 7.08 6B70cr 4.97 4.97 4.97 - 4.97 4.97 6B71d' 4.91 4.91 4.91 4.91 4.91 6B72C?' b.ll 5.11 5.11 5.11 5.11 6B73d' 4.68 4.68 4.68 4,68 4. fie 6B101C" 6.28 5.68 6.32 6.88 7.36 6B102d' 0.37 5.37 5.37 5.37 5.37 6B103cf 5.03 5.03 5.03 5.03 5.03 6B104d' 4.76 4.76 4.76 4.76 4.76 6B769 5.19 5,19 5.19 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 6B10e$ 4 . 79 4.79 4.79 4.79 4.79 7A25$ J. 44 5.44 5.44 5.44 5.44 7A26$ 32.80 9.64 11.72 11.80 9.96 7A559 ■..75 •;.75 4.75 4.75 4.75 7A569 8.84 47.48 27.20 7.96 12.60 7A57$ 4.72 4.72 4.72 4.72 4.72 7A89$ 4.84 4.84 4.84 4.84 4.84 7A90$ 4.92 4.92 4.92 4 . 92 4.92 Average 6.734 7.400 6.602 5.713 5.840 Table la. i:aze Learning by Inbred Rats. Rat ,f Day 51 Day 52 Day 53 Day 54 Day 55 6A71cf i).41 5.41 5.41 5.41 5.41 tklZiJ 5.76 5.76 5.75 5.76 5.76 6kl-id' 6.40 8.60 6.64 5.88 11.40 6B70cf 4.97 4.97 4.97 - 4.97 4.97 6371(5" 4.91 4.91 4.91 4.91 4.91 6B72C? 5.11 5.11 5.11 5.11 5.11 6B73cf 4.68 4.68 4.68 4.68 4.68 esioid' 12.60 6.68 5.60 6.56 6.68 6B102d" 5.37 5.37 5.37 5.37 5.37 esioscf 5.03 5.03 5.03 5.03 5.03 6B104d' 4.76 4.76 4.76 4.76 4.76 6B76$ 5,19 5.19 5.19 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 6B108$ 4.79 4.79 4.79 4.79 4.79 7A25$ 5.44 5.44 5.44 5.44 5.44 7A269 8.08 7.12 7.64 7.44 7.36 7A555 4.75 4.75 4.75 4.75 4.75 7A569 10.00 7.92 6.88 6.20 8.76 7A579 4.72 4.72 4.72 4.72 4.72 7A699 4.84 4.84 4.84 4.84 4.84 7A902 4.92 4.92 4.92 4.92 4.92 Averatje 5.844 5.522 5.353 5.416 5.707 Table la. Maz.e Learnintj by Inbred Rats. Rat r'^ Eay 56 Day 57 Day 58 Day 59 Day 50 6A71d' 5.41 5.41 5.41 5.41 5.41 6A72d' 5.76 5.76 5.76 5.76 b.76 6A73d' 7.44 7.00 6.24 6.48 7.04 6B70d' 4.97 4.97 4.97 4.97 4.97 6371^ 4.91 4.91 4.91 4.91 4.91 6B72cf 5.11 5.11 5.11 5.11 5.11 6B73cf 4.68 4.68 4.68 4.68 4.68 6B101cf 6.28 7.04 7.00 5.48 5.36 6B102cf 5.37 5.37 5.37 5.37 5.37 6E103C? 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B76$ 5.19 5.19 5.19 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 6BIO89 4.79 4.79 4.79 4.79 4.79 7AC55 5.44 5.44 5.44 5.44 5.44 7A265 6.88 9.52 7.40 7.20 8.76 7A55$ 4.75 4.75 4.75 4.75 4.75 7A569 18.16 9.24 8.32 13.24 34.72 7A579 4.72 4.72 4.72 4.72 4.72 7A89$ 4.84 4.84 4.84 4.84 4.84 7A909 4.92 4.92 4,92 4.92 4.92 Average 5.924 5.640 5.458 5.621 6.740 Table la. Llaze Learning by Inbred Rats. 30 Rat # Day 61 Day 62 Day 63 Day 64 Day 65 6A71cf 5.41 5.41 5.41 5.41 5.41 6A72J' 5.76 5.76 5.76 5.76 5.76 6A73cf 8.12 8.68 7.92 6.32 6.48 esvoc? 4.97 4.97 4.97 - 4.97 4.97 GB^lcf 4.91 4.91 4.91 4.91 4.91 6Bl2ay B2 Lay 83 Lay 84 Lay 8b 6A71cr 5.41 5.41 5,41 5.41 0.41 6A72cf 5.76 5.76 5.76 5.76 5.76 6A73cf 5.72 5.64 5.76 5.76 5.76 61700? 4.97 4.97 4.97 - 4.97 4.97 6871(1? 4.91 4.91 4.91 4.91 4.91 6B72d' 5.11 5.11 5.11 5.11 5.11 6B73cr 4.68 4.68 4.68 4.63 4. 63 esioid- 5.47 5.47 5.47 5.47 5.47 6B102cf 5.37 :3.37 5.37 5.37 5.37 6B103cf 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B76$ 5.19 5.19 5.19 5.19 5.19 6B77$ 5.00 5.00 5.00 5.00 5.00 6BIO85 4.79 4.79 4.79 4.79 4.79 7A25$ 5.44 5.44 5.44 5.44 5.44 7A26$ 7.44 41.80 7.36 6.80 27.88 7A55$ 4.75 4.75 4.75 4.75 4.75 7A565 23.72 15.48 8.72 10.56 8.56 7A579 4.72 4.72 4.72 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4.84 7A909 4.92 4.92 4.92 4.92 4.92 Average 5.095 7.335 5.379 5.535 6.345 Table la. "aze T.earniac; by Inbred Rata. Pat '^ ray 86 Day 87 lay 88 Day 89 Lay 90 6A71d" 5.41 5.41 5.41 5.41 5.41 6A72d' 5.76 5.76 5.76 5.76 5.76 6A73cf 5.76 5.76 5.76 5.76 5.76 6B70cr 4.97 4.97 4.97 - 4.97 4.97 6B71cf 4.91 4.91 4.91 4.91 4.91 6B72cr 5.11 5.11 5.11 5.11 5.11 6B73d' 4.68 4.68 4.68 4.68 4.68 eBlOld' 5.47 5.47 0.47 5.47 0.47 6B102d' 5.37 5.37 J. 37 5.37 5.37 GBlOSd" 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B769 5.19 5.19 5.19 5.19 5.19 6B779 5.00 5.00 5.00 5.00 5.00 6BIO85 4.79 4.79 4.79 4.79 4.79 7A259 5.44 5.44 5.44 5.44 5.44 7A25$ 11.08 7.76 12.44 9.88 41.20 7A559 4.75 4.75 4.75 4.75 4.75 7A56$ 7.44 7.00 7.44 7.08 15.00 7A579 4.72 4.72 4.72 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4. 34 7A90$ 4.92 4.92 4.92 4.92 4.92 Average 5.495 5.316 5.560 5.421 7.290 Table la. maze Learning oy Inbred Rats. 36 Rat ,^ Day 91 Day 92 Day 93 Day 94 Day 95 eAVicf b.41 5.41 5.41 D.41 0.41 6A72d' J. 76 •3.76 5.76 5.76 0.76 6A73d' 5.76 5.76 5.76 5.76 5.76 6B70C? 4.97 4.97 4.97 • 4.97 4.97 eBVlcf 4.91 4.91 4.91 4.91 4.91 6E72C? 5.11 5.11 5.11 5.11 5.11 6B7?cf •;.68 4.68 4.66 4.68 4.68 esioicf 5.47 5.47 5.47 5.47 5.47 6B102C? 5.37 5.37 5.37 5.37 5.37 eBlOScf 5.03 5.03 5.03 5.03 5.03 6B104cf 4.76 4.76 4.76 4.76 4.76 6B76$ 5.19 5.19 5.19 5.19 5.19 63775 5.00 5.00 5.00 5.00 5.00 6EIO85 4.79 4.79 4.79 4.79 4.79 7A25$ 5.44 5.44 5.44 5.44 5.44 7A26$ 17.76 36.88 24.08 20.20 12.68 7A559 4.75 4.75 4.75 4.75 4.75 7A569 7.76 13.56 9.32 9.16 7.12 7A57$ 4.72 4.72 4.72 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4.84 7A90$ 4.92 4.92 4.92 4.92 4.9:: Average 5.829 7.015 6.204 6.011 5.556 Table la. I^aze Learning "by Inbred Hats. 7>1 Rat # Day 96 Day 97 Day 90 Day 99 Day 100 SAVld" D.41 ...41 0.41 0.41 U.41 6A72cr J. 76 5.76 5.76 5.76 5.76 6A73cr 5.76 5.76 5.76 5.76 5.76 6B70cr 4.97 4.97 4.97 • 4.97 4.97 6B71cr 4.91 4.91 4.91 4.91 4.91 6B72d' 5.11 5.11 5.11 5.11 5.11 6B73d' 4.68 4.68 4.68 4.68 4.60 6E101cf 5.47 5.47 5.47 5.47 5.47 631020' 5.37 5.37 5.37 5.37 5.37 6B103cf 5.03 5.03 5.03 5.03 5.03 6B104d' 4.76 4.76 4.76 4.76 4.76 6B76} 5.19 5.19 5.19 5.19 5.19 6L779 5.00 5.00 5.00 5.00 5.00 6BIO82 4.79 4.79 4.79 4.79 4.79 7A259 5.44 5.44 5.44 5.44 5.44 7A26$ 19.30 16.24 23.20 22.48 21.92 7A55$ -.75 4.75 4.75 4.75 4.75 7A565 7.08 5.84 6.28 6.08 6.32 7A57$ 4.72 4.72 4.7C 4.72 4.72 7A899 4.84 4.84 4.84 4.84 4.84 7A90$ 4.92 4.92 4.92 4.92 4.92 Average 5.8^^3 5.893 5.893 5.893 5.693 Table la. u:aze Learning by Inbred Rats. Rat -^ I''ailed to learn. Days required to learn. 38 6A71d' 6A72c? 6A73cf 6B70d" 6B71d' 6B72d' 6B73d' 6J3101cf 6S102U 63103cr 631040" 6376$ 5B77i^ 6BIO89 7A25$ 7A26$ 7A55$ 7A569 7A57$ 7A899 7A909 37 40 82 23 27 7^0 33 61 33 12 17 24 28 14 39 100+ 14 100+ 17 16 22 :otal 2 : Average 36. oi Table la. I'.nze Learning by Inbred Kr.tg. 39 First trial Rat i after 60 days' rest. eAVld* 20.20 6A72d' 77.00 6A73cf 13.00 6B70cf 38.20 6B71'J' 86.00 6B12J' 36.40 6B73C:? 19.20 6131010^ 164.60 021020' 41.60 eslOScf 109.20 6B104cf 84.60 6B769 68.80 63779 36.60 6BIO89 120.80 7A259 383.60 7A269 7A559 89.20 7a569 7A579 21.40 7A899 51.60 7A909 87.60 Average 61.558 Table lb. Absolute Retention of Inbred Hats, 40 Day 1 Day 2 Day 3 Lay 4 Day 5 CO. 16 7.72 9.00 fa. 44 6.88 CO. 64 6.48 5.56 'o.lO U.5G 7.80 9.24 6.32 8.56 8.48 2;2.20 12.76 17.02 • 13.32 10.36 34.32 10.24 7.40 a. 84 6.08 13.12 5.72 6.00 4.88 ■i . 86 9.20 4.96 4.96 4.96 4.96 52.68 10.12 23.96 14.40 21.52 :^8.eo 9.80 12.12 17.80 11.96 118.08 23.32 20.32 8,12 S.72 25. 76 5.60 6.00 5.72 5.52 29.12 19.12 11.52 5.12 0.12 15.20 11.36 5.84 10.24 6.56 39.04 6.56 17. G8 10.16 6.40 69.40 8,04 7.32 8.40 13.96 Rat jj: 6A71d' 6A72d' 6A73:f 6S70c? 6I371d' 65720^ 66730- 6B101C? 6B102d" 6B103C? 6B104u 6376$ 6B77$ 6B108$ 7-V259 7A269 7A55$ 42.20 50.36 6.04 14.60 7A56$ 7A57$ 7A899 7A909 Average 35.415 12.208 10.069 9.560 6.069 Table Ic. Ilaze Relearnin*^ uy Inbred Rats. 11.40 8.48 9.68 21.28 9.32 32.44 10.24 5.40 O.40 U.40 51.32 9.84 6.28 5.84 ..84 41 Rat if ray 6 Day 7 Day 8 Day 9 Lay 10 6A71cr 6.72 6.36 10.44 6.96 6.64 6A72cf ::..56 b.56 5. 56 b.56 J.5G 6A73J' 16.56 9.04 10.92 10.20 13.72 6370c' 5.88 6.12 5.12 5.12 5.12 6B71cf 7.36 8.56 5.76 5.72 5.36 63720? 4.88 4.88 4.88 4.88 4.88 6B73ci' 4.96 4.96 4.96 4.96 4.96 6B101cf 10.00 17.80 8.24 9.44 7.48 esiosd" 19.68 11.68 6.84 7.12 6.48 6B103cf 5.92 5.36 5.36 5.36 5.36 681040? 5.24 4.84 4.84 4.84 4.84 6B769 -.12 5.12 5.12 5.12 5.12 6B77$ 8.80 7.12 5.84 5.24 0.24 6BIO89 7.76 6.56 5.04 5.04 5.04 7A25$ 7.12 9.76 7.12 7.20 6.88 7A269 7A559 6.56 13.68 10.64 7.32 7.48 7A56$ 7A579 6.40 6.88 8.28 7.16 14.08 7A899 5.40 5.40 .J. 40 5.40 5.40 7A90$ 5.84 5.84 5.84 5.84 0.84 Average 7.672 7.659 6.642 6.232 6.604 •le Ic. '.;aze Relearning by Inbred Rats. 42 Rat if Day 11 Day 12 Day 13 Day 14 Lay 15 6A71d' 6.32 8.12 7.92 6.04 6.00 6A72d' 0.5G 5.56 5.56 5.56 5.50 6A730' 14.76 11.72 8.72 9.28 7.84 6B70cf b.l2 5.12 5.12 - 5.12 5.12 6B71cf 5.36 5.36 5.36 5.36 5.36 6B72d' 4.88 4.88 4.88 4.88 4.88 6B73d' 4.96 4.96 4.96 4.96 4.96 eBlOlc? 5.96 5.96 5.96 5.96 5.96 6B102c:r 7.76 7.48 8.32 6.48 6.60 6E103C? 5.36 5.36 5.36 5.36 J. 36 63104(.i' 4.84 4.84 4.84 4.84 4.84 6B76$ 5.12 5.12 5.12 5.12 5.32 6B779 5.24 5.24 5.24 5.24 5.24 6B106$ 5.04 5.04 5.04 5.04 5.04 7A25$ 5.80 5.80 5.80 5.80 5.80 7A26$ 7A559 5.64 5.64 5.64 5.64 5.64 7 AS 6 9 7A579 8.84 5.92 10.20 5.60 5.60 7A699 5.40 5.40 5.40 5.40 5.40 7A909 5.84 5.84 5.84 5.64 5.84 Average 6.200 5.966 6.067 5.660 5.587 Table Ic. Haze Relearnint; ^y Int^red Rr.ts. 43 Rat ;'^ Lay 16 Lay 17 Lay 18 Lay 19 Lay CO eA7icr 6.16 6.72 7.00 9.56 8.28 6A72C? b.S6 5.56 5.56 5.56 5.56 6A73cf" 8.84 8.88 9.48 12.92 8.36 6E70cf 5.12 5.12 5.12 - 5.12 5.32 6E71d' 5.36 5.36 5.36 5.36 5.36 6B72cf 4.88 4.88 4.88 4.88 4.88 6B73cr 4.96 4.96 4.96 4.96 4.96 6B101d 5.96 5.96 5.96 5.96 5.96 6BlQ2d 6 . 52 6.40 5.72 6.36 6.28 631030" 5.36 5.36 5.36 5.36 5.36 6B104d" 4.84 4.84 4.84 4.84 4.84 6B765 5.12 5.12 5.12 5.12 5.12 6B77$ 5.24 5.24 5.24 5.24 5.24 6P108$ 5.04 5.04 5.04 5.04 5.04 7A25$ 5.80 5.80 5.80 5.80 5.80 7A269 7A55$ 5.64 5.64 5.64 5.64 5.64 7A56$ 7A579 5.60 5.60 5.60 5.60 5.60 7A899 5.40 5.40 5.40 5.40 5.40 7A909 5.84 5.84 5.84 5.84 5.84 Average 5.634 5.669 5.680 6.029 5.718 Table Ic. "a.ze Relearning by Inbred Rr.ts 44 Rat 7/ Day 21 Lay 22 Day 23 Day 24 lay 25 eA71cf 15.24 7.28 7.32 8.36 6.60 6A72cr U.56 D.56 5.56 5.56 5.56 6A73d' 7.72 11.44 10.80 14.36 11.48 6B70cf 5.12 5.12 5.32 ■ 5.12 5.D2 6B71o^ 5.36 5.36 5.36 5.36 5.36 6E72cf 4.86 4.88 4.88 4.88 4.88 6B15(f 4.96 4.96 4.96 4.96 4.96 6B101C' 5.96 5.96 5.96 5.96 5.96 6B102c^ 6.20 6.40 7.20 6.72 5.84 6E103cr 5.36 5.36 5.36 5.36 5.36 6B104d' 4.84 4.84 4.84 4.84 4.84 6B769 5.1?. 5.]2 5.32 5.]2 5.12 6E77$ 5.24 5.24 5.24 5.24 5.24 6B108$ 5.04 5.04 5.04 5.04 5.04 7A25$ 5.80 5.80 5.80 5.60 5.80 7ii^69 7A559 5.64 5.64 5.64 5.64 5.64 7A569 7A579 5.60 5.60 5.60 5.60 5.60 7Ae99 5.40 5.40 5.40 5.40 5.40 7A909 5.84 5.84 5.84 5.64 5.84 Average 6.046 5.834 5.844 6.061 5.771 Table Ic. Uaze Relearniriu by Inbred Rats. Rat # Lay 26 Lay 27 Day 28 Lay 29 Lay 30 6A71cf 10.60 7.64 9.16 9.06 7.86 6A72cr 0.56 0.56 5.56 0.56 0.56 6A73d' lis. 00 9.04 11.64 10.36 11.08 6B70d' 5.12 5.12 5.12 - 5.12 5.12 6B71cf b.36 5.36 5.36 5.36 5.36 6372^^ 4.88 4.88 4.88 4.88 4.88 6B73cf 4.96 4.96 4.96 4.96 4.96 6B101cf 5.96 5.96 5.96 5.96 5.96 6B102cf 5.84 5.84 5.84 5.84 5.84 6B103cr 5.36 5.36 5.36 5.36 5.36 6B104C' 4.84 4.84 4.84 4.84 4.84 6B76$ 5.12 5.12 5.12 5.12 5.12 6B779 5.24 5.24 5.24 5.24 5.24 6BIO89 5.04 5.04 5.04 5.04 5.04 7A259 5.80 5.80 5.80 0.60 5.80 7A26§ 7A55$ 0.64 5.64 5.64 5.64 5.64 7A569 7A57$ 5.60 5.60 5.60 5.60 5.60 7A89$ 5.40 5.40 5.40 5.40 5.40 7A909 5.84 5.84 5.84 5.84 5.64 Average 6.] 66 5.697 5.914 5.842 5.817 Table Ic. I'aze Relearnine; by Inbred Eats. Rat # Day 31 Day 3'^ Day 33 Day 34 Lay 35 6A71d' 10.64 9.08 6.72 8.04 6.84 6A72d' J. 56 5.56 5.56 5.56 5.56 6A73d' 9.92 11.56 3.88 11.4 8 14.44 eE7Cd^ 5.12 5.12 5.12 ■ 5.12 5.12 6B71c:? 5.36 5.36 5.36 5.36 5.36 6B72c^ 4.88 4.88 4.88 4.88 4.88 6373c^ 4.96 4.96 4.96 4.96 4.96 6B101cf 5.96 5.96 5.96 5.96 5.96 6E102d' 5.64 5.84 5.84 5.84 5.84 esiosc? 5.36 5.36 5.36 5.36 5.36 6B104d' 4.84 4.84 4.84 4.84 4.84 6B769 5.12 5.12 5.12 5.12 5.12 6B77$ 5.24 5.24 5.24 5.24 5.24 62108$ 5.04 5.04 5.04 5.04 5.04 7A259 5.80 5.80 5.80 5.80 5.80 7i\26$ 7A55$ 5.64 5.64 5.64 5.64 5.64 7A56$ 7A579 5.60 5.60 5.60 5.60 5.60 7A899 5.40 5.40 5.40 5.40 5.40 7A90$ 5.84 5.84 5.84 5.84 5.84 Average 5.901 5.905 5.640 5.846 5.939 Table Ic. I!oze rvelearning by Inbred Rata. 47 Rat # Cay 36 Day 37 Day 38 Day 30 Day 4 0 eA71c? 8.00 7.24 8.16 8.96 8.36 6A72cf L..56 5.56 5.56 5.56 5.56 6A73cf 12.9L-' 14.36 12.44 9.04 6.88 6B70tf 5.:2 5.32 5.12 - 5.12 5.12 65710? 5.36 5.36 5.36 5.36 5.36 6E72cf 4.88 4.88 4.88 4.88 4.88 6B73d' 4.96 4.96 4.96 4.96 4.96 63101cr 5.96 5.96 5.96 5.96 5.96 6B102d^ 5.84 5.84 5.84 5.84 5.84 6B103O' 5.36 5.36 5.36 5.36 5.36 6B104C? 4.84 4.84 4.84 4.84 4.84 6B76$ 5.12 5.12 5.]2 5.12 5.12 6B77$ 5.24 5.24 5.24 5.24 5.24 6B10e5 5.04 5.04 5.04 5.04 5.04 7A25$ 5.80 5.80 5.80 5.80 5.80 7A269 7A55$ b.64 5.64 5.64 5.64 5.64 7A56$ 7A57$ 5.60 5.60 5.60 5.60 5.60 7A89$ 5.40 5.40 5.40 5.40 5.40 7A90$ 5.84 5.84 5.84 5.84 5.84 Average 5.920 5.956 5.903 5.766 5.'726 Table Ic. Haze Relearning by Inbred Rats. Rat ?/ Day 41 Day 42 Day 43 Day 44 Lay 45 eA?!^? 7.40 10.56 8.36 10.12 9.68 6A72d' 0.56 5.56 5.56 5.56 5.56 6A73cf e.52 9.00 9.88 7.48 10. ]2 6r.70d" 5.12 5.12 5.12 - 5.12 5.12 6B71cf 5.36 5.36 5.36 5.36 5.36 6B72d' 4.88 4.88 4.88 4.88 4.88 6B73cf 4.96 4.96 4.96 4.96 4.96 esioic? 5.96 5.96 5.96 5.96 5.96 6B102cf 5.84 5.84 5.84 5.84 5.84 63103d" 5.36 5.36 5.36 5.36 5.36 6B104cf 4.84 4.84 4.84 4.84 4.84 6376$ 5.12 5.12 5.12 5.12 5.12 6E77$ 5.24 5.24 5.24 5.24 5.24 6B10e$ 5.04 5.04 5.04 5.04 5.04 7A25$ 5.80 5.80 5.80 5.80 5.80 7A26$ 7A559 5.64 5.64 5.64 5.64 5.64 7A56$ 7A579 5.60 5.60 5.60 5.60 5.60 7A899 5.40 5.40 5.40 5.40 5.40 7A909 5.84 5.84 5.84 5.84 5.84 Average 5.657 5.848 5.779 5.745 5.861 Table Ic. l!aze Relearning by Inbred Rats. Rat # Day 4G Day 4 7 Day 48 Day 49 Day 10 6A71d' 11.88 8.S2 9.64 10.08 8.04 6A72d" i.56 5.56 5.56 5.56 0.56 6A73C/ 11.16 10.40 11.28 7.84 8.64 63706^ 5.12 5.12 5.3 2 - 5.32 5.12 6B71cf b.36 5.36 5.36 5.36 5.36 6272^ 4.88 4.68 4.88 4.88 4.88 6B73d^ 4.96 4.96 4.96 4.96 4.96 6E101d' 5.96 5.96 5.96 5.96 5.96 6B10iid' 5.84 5.84 5.84 5.84 5.84 6B103d- 5.36 5.36 5.36 5.36 5.36 6B104C? 4.84 4.84 4.84 4.84 4.84 6B76$ 5.32 5.12 5.12 5.12 5.12 6E77$ 5.24 5.24 5.24 5.24 5.24 63108$ 5.04 5.04 5.04 5 . 04 5.04 7A25$ 5.80 5.80 5.80 5.80 5.80 7A26$ 7A55$ 5 . 64 5.64 5.64 5.64 5.64 7A56$ 7A57$ 5.60 5.60 5.60 5.60 5.60 7Ae95 U.40 5.40 5.40 5.40 5.40 7A90$ 5.84 5.84 5.84 5.84 5.64 Average 6.032 5.615 5.920 5.762 5.697 Table Ic. L'.aze Kelearnirifc by Inbred Eats. bO Failed Days required Rat # to relenrn. to relearn. eA71cf 1 50-f 6A72d^ 3 6A73cf 1 50-^ 6r.70d" " 8 6E71d' 10 6372^ 4 6373^" 2 SElOld" 11 6B102cf 25 631030- 7 6r.l04d" 7 6276$ 4 6E779 9 6B108v 8 7A255 11 7A26$ 7A55$ 11 7A56$ 7A579 14 7A699 3 4 7A90$ Total 2 : Average IS.aS-i- Table Ic. IJaze Relearning by Inbred Kats. f)! Rat -r^ Body length in I.un. Body weight in grna. Brain weight in grms. Gord weight in grna. Water in brain eAVld" 199. ■203.7 1.''413 .5590 78.27 6A72d' 207. 218.6 l.'7e29 .5737 78.60 6A73cf 205. 153.0 1.7113 .5916 78.78 6B70cf 202. 204.0 1.7737 .5331 78.64 6E71d' 203. 193.2 1.7773 .5223 78.46 65720' 198. 191.2 1.7572 .5081 78.71 6B73d' 204. 215.4 1.7611 .5478 78.96 6B101o^ 210. 220.3 1 7855 . 5892 78.21 6E102J 200. 193.5 1.7646 .5454 78.00 6B103cr 215. 240.2 1.7626 .5500 78.21 6B104cf 208. 224.9 1.6053 .5208 78.33 6B76$ 188; 168.4 1.7804 .5380 78.59 6E77$ 177. 139.0 1.6197 .4610 78.77 6B108$ 194. 165.1 1.7098 . 5033 78.32 '7A259 195. 175.0 1.7058 .5563 78.35 7A269 189. 166.6 1.6559 .5227 78.38 7A559 181. 147.2 1.6055 .4775 78.69 7A56$ 177. 126.5 1.5189 .4883 78.78 7A57$ 176. 136.6 1.6041 .4936 78.56 7A89$ 193. 170.9 1.6565 .5304 76.31 7A909 162. 144.5 1.6563 .4868 78.51 Average 195.38 180.855 1.71122 .52852 78.497 Table Id. Anatomical Data of Inbred Kats. b2 Rat fi Water %• Brain wt. [c Brain wt. Aje in cord in relation to in relation to killed, ■}"■ body length. body weight. Days. eA?!^ 70.89 .87503 .85483 234. 6A7:::d" 71.. -56 .86130 .81560 234. 6A73cr 70.25 .83478 1.11850 190. eBiOcf 72.22 .87807 .86912 190. 6B71cr 72.01 .87552 .91993 190. 6E72C? 72.56 .88747 .91904 190. 6B73d" 72.65 .86289 .81760 390. 6E101cf 72.00 .85024 .81049 262. 6E102cr 70.92 .88200 .91194 178. 6E103cf 71.33 .81981 .73361 178. 6P104c/ 71.39 .86793 .80271 178. 6E76$ 72.75 .94702 1.05701 175. 6E77$ 72.67 .91508 1.16525 175. 6E10e$ 71.47 .88134 1.03561 178. 7A25$ 71.63 .87477 .97474 239. 7A26$ 71.55 .87614 .99394 239. 7A559 71.41 .88702 1.09035 165. 7A56$ 72.58 .85763 1.20071 231. 7A579 71.39 .91142 1.17430 165. 7A699 71.49 .85829 .96928 206. 7A90$ 71.86 .91005 1.34623 206. Average 71. 723 .87685 .97052 200. :able Id. Anatomical ];ata of Inbred Kate, Rat r'i ray 1 Day Day Lay 4 Jiay 5 G{C\V)28cf 209.56 42.64 24.04 12. '-'6 107.24 S(CW)29d- 128.40 32.44 10.44 10.40 31 . 36 S(BC)62cr 288.24 76.52 48.00 8.40 7.56 S(BC)63d' .^65.56 219.56 77.04 ■33.40 15.44 S(CAB)70cf 509.72 79.32 41.76 16.16 21.80 S(CW)83d' 192.96 31.20 9.20 6.84 8.64 S(CB)98cf 827.52 187.96 50.16 45.00 54.00 S{C^)99d 1125. ]2 596.24 120.60 48.96 22.80 S(CH)l37c' 120.36 23.44 9.52 5.24 7.20 S(CH)l38d" 6 50.32 23.36 9.00 5.76 22.48 S(CH)l.'59cf 72.80 41.56 25.92 12.84 4.96 S(HC)239 528.76 101.20 30.76 50.00 19.48 S(HC)25$ 149.32 24.40 17.24 13.04 6.64 S(HW)599 319.24 191.88 97.92 27.28 41.84 S(H\7)60$ 297.60 38.12 59.36 17.24 13.48 S(BC)64$ 266.44 43.84 37.12 37.40 35.64 S(BC)66$ 259.56 117.40 78.80 35.64 34.04 S(BC)679 254.52 91.56 65.88 41.00 33.36 S(BC)699 3730.44 277.16 277.64 149.48 62.56 S(CW)e4 182.64 69.64 24.04 14.04 12.84 S(CY0859 128.60 16.08 16.84 5.88 4.52 Average 505.128 110.739 53.851 28.404 25.613 Table Ila. I'aze Learnint; by ITormal Rats. Rat # ray 6 Day 7 Day 8 Lay 9 Day 10 5' cCcvOssc? IfS.D? 11. ]6 6.24 6.48 5.56 S(CW)29d' 8.f)2 5.80 5.00 5.56 7.56 E(BC)62cf 7.96 7.26 6.08 5.12 37.00 S(BC)63tf 9.68 7.08 6.60 - 6.24 5.84 S{C/EB)10d 11.5:-' 7.84 7.24 8.36 6.64 S(OT)83d 16.16 6.00 5.72 13.28 6.32 S(CB)98d' 26.32 19.72 21.08 15.08 7.76 G(CI3)99o 20.80 16.64 15.88 14.60 16.40 S(CH)l37cf 6.36 4.86 5.20 5.52 7.84 S(CH)l38d" 8.04 8.48 7.28 6.84 5.08 S(CH)l39c^ 6.04 6.]6 4.52 4.44 5.20 S(HC)239 51.16 25.32 38.68 23.60 12.12 S(HC)259 7.56 8.24 5.44 8.92 4.88 S(HW)59$ 39.36 23.68 20.84 22.20 5.08 S(H\V)60$ 6.12 27.66 24.52 43.64 13.32 S(BC)649 15.64 12.32 13.28 9.32 6.76 S(BC)669 27.68 9.04 12.72 9.28 11.68 S(EC)679 38.44 29.68 20.28 15.68 15.80 S(BC)699 22.80 32.92 D4.04 8.80 6.80 S(C\V)849 11.32 6.80 6.16 19.76 5.72 s(cw)e5$ 7.08 4.40 5.08 6.52 6.64 Average 17.366 13.381 11.994 12.440 9.619 Table Ila. I.;aze Learninti by liormal Kats, Rat # Day 11 Day 12 Day 13 Day 14 Day It) S(CV;)28cf 5.04 5.24 'j.2t< u.V.b •j.-^t^ S(CW)29c 5.28 4.92 5.28 5.16 5.16 S(BC)62cr 5.20 10. ]6 5.36 4.72 4.66 S(BC)63c- 5.60 6.00 5.84 - 5.84 5.46 S(CA2)70 6.44 5.56 16.00 S.]6 6.08 sCcvOsscf 5.52 4.76 5.48 6.52 4.88 S(CB)98d" 6.88 10.68 8.32 7.20 14.36 S(CB)99cf 13.40 16.08 9.00 6.52 6.80 S(CH)l37cf 5.04 4.96 4.60 4.87 4.87 S(CH)l38a 4.56 4.72 5.28 5.36 4.56 8(^)1390? 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 10. ]6 9.56 9.36 9.84 10.28 F(HC)25$ 4.56 4.72 4 . 72 4.72 4.72 S(HV/)599 11.68 8.88 8.88 9.80 7.44 S(m7)60$ 9.60 13.20 10.40 11.72 7.96 S(BC)64$ 7.00 8.12 6.32 9.72 9.44 S(BC)669 6.32 10.28 11.24 7.00 12.68 S(BC)67$ 12.20 12.32 6.48 9.04 8.88 S(BC)69$ 8.24 7.00 7.60 9.08 15.20 S(C\V)849 5.16 4.84 4.60 4.67 4.87 S(CW)855 8.60 6.20 5.68 4.84 4.48 Average 7.295 7.748 7.354 6.904 7.277 Table Ila, L'aze Learning by Normal Rats. Rat # Day 16 Lay 17 Lay 18 Lay 19 Lay 20 S(C\V)2aa^ J. 26 5.28 5.28 5.28 ;..28 S(C\V)29cf 1;.]6 5.16 5.16 5.2 6 5.26 5(80)620^ 4.64 ■'■ . 58 4.68 4.68 4.68 S(BC)63d' 5.:2 5.84 7.36 - 6.32 5.64 S{C/EB)'?Oo 5.84 5.80 5.40 8.44 7.00 S(CW)83cr 6.52 6.24 5.36 4.68 4.64 S(CL)98cr 8.88 7.52 6.44 6.92 5.72 C(CE)99c? 5.64 7.16 6.32 8.16 6.44 S{CH)l37d' 4.87 4.87 4.87 4.87 4.87 S{CK)l3aG^ 9.52 4.52 5.60 4.64 4.80 S(CH)l39o 4.72 4.72 4.72 4.72 4.72 S(HC)239 6.92 7.08 5.44 6.64 5.36 S(HC)25$ 4.72 4.72 4.72 4.72 4.72 S{ir,7)59$ 10.28 5.2 2 5.04 4.52 4.69 S(H\V)60$ 12.52 7.32 4.56 8.40 5.52 S(BC)649 6.48 10.72 9.48 11.88 7.12 S(BC)66$ 8.00 10.88 9.00 6.88 11.24 S(BC)679 8.48 11. ]2 7.92 6.68 7.24 S(BC)699 7.04 6.68 7.00 7.24 8.28 S(C\V)849 -;.87 4.87 4.87 4.87 4.87 S(CW)659 4.72 '..68 4.68 4.68 4.68 Average 6.687 6.428 5.900 6.209 5.851 Table Ila. Llaze Learnint by "orruil Hats. L.7 Rat # Lay 21 Lay 22 Day 23 Lay 24 Lay 2b £(C;\')28tf 0.28 L).2b U.28 J. 2b v'.;;b S(C\v)29c; 15.16 5.16 b.]6 b.l6 b.]6 8(130)620" 4.68 4.68 4.68 4.68 4.68 S(i;C)63o' 6.52 5.36 5.00 - 5.28 b.21 S(C/E2)70u 6.44 5.56 5.48 4.92 b.32 S(CV/)83d- 4.84 ^1 . 72 4.72 4.72 4.72 S(CB)98cr 8.52 6.96 5.92 6.20 6.40 S(CB)99c? 6.04 7.20 6.84 7.72 5.76 S(CH)l37cf 4.87 4.87 4.87 4.87 4.87 S(CK)l38cr 5.04 4.83 4.83 4.83 4.83 S(CH)l39cf 4.72 4.72 4.72 4.72 4.72 S(HC)239 5.68 5.56 5.32 5.16 L>.35 S(HC)£59 4.72 4.72 4.72 4.72 4.72 S(K';V)59$ 4.89 4.89 4.89 4.89 4.69 S(}IV060$ 4.72 5.08 4.60 4.80 4.80 S(BC)64$ 5.68 5.96 7.68 5.80 6.32 S(BC)66$ 6.56 11.76 10.84 12.04 9.08 G(LC)e7$ 7.12 9.68 9.56 8.48 6.80 S(BC)69$ 5.20 5.60 5.24 b.35 b.35 S(C\Y)e4$ 4.87 4.87 4.87 4.87 4.87 S(C^)S59 .^. .6£ -^ .68 4.68 4.68 4.68 Average 5.650 5.816 5.710 5.675 5.420 Table Ila. L-aze Learning by formal Hats. 58 Rat # Day 26 Day 27 Day 28 Day 29 Day 30 S(CV/)28cr .'.28 5.28 b.28 0.28 0.2b S(CY/)29d' D.16 5.16 0.16 5.16 5.16 S(BC)62o' 4.68 4.68 4.68 4.68 4.68 S(BC)63cf 5.21 5.21 5.21 • 5.21 5.21 S(C/EB)70cr 5 . 32 .0 . 32 5.32 0.32 5.32 S(CV/)83o^ 4.72 4.72 4.72 4.72 4.72 S(CB)98d' 6.32 S.08 8.60 8. 92 9.80 8(03)990- 7.80 7.4C £.88 5.52 5.44 S(CH)l37cf 4.87 4.87 4.87 4.87 4.87 S(CK)l36cf 4.83 4.83 4.83 4.83 4.83 S(CH)l39cf 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)259 4.72 4.72 4.72 4.72 4.72 s(mv)59$ 4.89 4.89 4.89 4 . 89 4.89 S(H\7)609 4.80 4.80 4.80 4.80 4.80 S(BC)649 6.16 5.64 6.12 5.56 5.84 S(BC)669 7.72 7.92 7.92 9.28 7.68 fi(3C)679 5.72 5.72 6.08 6.68 5.96 S(BC)699 5.35 5.35 5.35 5.35 0.35 S(C7/)849 4.87 4.87 4.87 4.87 4.87 S(CW.)859 4.r,8 4.68 4.68 4.68 4.68 Average 5.389 5.442 5.479 5.496 5.437 Table Ila. IJaze Learnirit, by Korinal hats. Rat ^^ Day 31 Day 32 Day 33 Day 34 Day 35 S(CW)28d' J. 28 5.28 5.28 5.28 5.28 S{CW)29d' ij.l6 5.16 5.16 5.16 5.16 S(3C)62d^ 4.68 4.68 4.68 4.68 4.68 S(BC)63d' 5.21 5.21 5.21 - 5.21 5.21 s(cAB)70cr 5.32 5.32 5.32 5.32 5.32 S(CW)63c? 4.72 4.72 4.72 4.72 4.72 S(CB)98cf 10.72 3.72 8.16 11.40 6.56 S(C3)99cf 5.24 5.40 5.40 5.40 5.40 S(CH)l37d' 4.87 4.87 4.87 4.87 4.87 S(CIl)l30c^ 4.83 4.83 4.83 4.83 4.83 S(CH)l39cf 4.72 4.72 4.72 4.72 4.72 S(]IC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)25$ 4.72 4.72 4.72 4.72 4.72 S(HV0592 4.89 4.39 4.89 4.89 4.89 S(H\7)60$ 4.80 4.80 4.80 4.80 4.80 S{BC)645 5.68 ::.69 5.69 5.69 5.69 S(3C)66$ 12.76 10.76 8.40 7.80 8.64 S(3C)675 5.84 5.52 5.84 5.73 5.73 S(BC)699 5.35 5.35 5.35 5.35 5.35 S(C\V)84$ 4.87 4.87 4.87 4.87 4.67 S(C\7)859 4.68 4.68 4.68 4.68 4.68 Average 5.700 5.502 5.378 5.499 5.308 Table Ila. Maze Learnin,j by Mornal Rata, (J 'J Rat ■!!■ Day 36 Day 37 Day 38 Day 39 Day 40 s(c;v/)2acr b.28 b.28 5.28 L.28 5.28 S(CW)29>^ 4.68 4.68 4.68 Average 5.272 5.249 5.327 5.363 5.316 Table Ila. :iaze Learnint: by Normal Rats, Rat # Day 41 Day 42 Day 43 Day 44 Day 45 S(CW)28cr 5.26 5.26 5.28 5.28 5.28 S(CW)29cf 5.16 5.16 5.16 5.15 5.16 S(BC)62J' 4.66 4. 68 4.68 4.68 4.68 S(3C)63d' 5.21 5.21 5.21 - 5.21 5.21 S(C/S3)70cf 5.32 5.32 5.32 5.32 5 . 32 S(GW)63d" 4.72 4.72 4.72 4.72 4.72 S(CB)98d' b.33 5.33 5.33 5.33 5.33 S(CB)99cr 5.40 5.40 5.40 5.40 5.40 S(CIl)l37u' 4.87 4.87 4.87 4.87 4.87 S(CH)l38o' 4.83 4.83 4.83 4.83 4.83 S(CH)l39cf 4.72 4.72 4.72 4.72 4.72 S(HC)235 5.35 5.35 5.35 5.35 5.35 S(HC)259 4.72 4.72 4.72 4.72 4.72 S(H\V)599 4.89 4.89 4.89 4.89 4.89 S(irv/)60$ 4.80 4.80 4.80 4.80 4.80 S(BC)645 5.69 5.69 5.69 5.69 5.69 S(3C)66$ 10.60 15.44 11.28 S.64 12.72 S(3C)679 5.73 5.73 5.73 5.73 5.73 S(BC)69$ 5.35 5.35 5.35 5.35 5.35 S(CW)649 4.87 4.87 4.87 4.87 4.87 S(C\'/)85$ 4.68 4.68 4.68 4.68 4.68 Average 5.343 5.573 5.375 5.250 5.444 Tabic I la. I'aze Learning by ITomal Rats. 62 Rat ;/ ray 4( Day 47 Day 48 Day 49 Day 50 G(CW)28cr ■J, 26 u.2b v. 28 b.28 D.28 S(CW)29d' 5.16 5.16 5.16 5.16 5.15 S{BC)62c/ 4.68 4.68 4.68 4.68 4.68 S(BC)63cf 5.21 5.21 5.21 - 5.21 5.21 S(C/EB)70d' 5.32 5.32 5.32 5.32 5.32 S(CW)83d' 4.72 4.72 4.72 4.72 4.72 S(CB)98d' 5.33 5.33 5.33 5.33 5.33 S(CB)99d' 5.40 5.40 5.40 5.40 5.40 S(CH)l37d' 4.87 4.87 4.87 4.87 4.87 5(^)1380? 4.83 4.83 4.83 4.83 4.83 S(CK)l39d' 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)259 4.72 4.72 4.72 4.72 4.72 S(H\7)592 4.89 4.89 4.89 4.89 4.89 S(H\7)609 4.80 4.80 4.80 4.80 4.80 S(3C)64§ 5.69 5.69 5.69 5.69 5.69 S(3C)66$ 9.32 6.80 6.48 7.56 8. OS S(BC)67$ 5.73 5.73 5.73 5.73 5.73 S(BC)69$ 5.35 5.35 5.35 5.35 5.35 S(CW)84$ 4.87 4.b7 4.87 4.87 4.87 S(CV0855 4.68 4.68 4.68 4.68 4.68 Average 5.282 5.162 5.147 5.198 5.223 Table Ila. Haze Learning by Normal Rats. h^ Rat # Day 51 Day 52 Day 53 Day 54 Day 55 S(C^7)28cf b.26 5.26 5.28 5.2b 5.28 S{CW)29d' 5.16 5.16 5.16 5.16 5.16 S(BC)62cf 4.68 4.68 4.68 4.68 4.66 S{BC)67>J 5.21 5.21 5.21 - 5.21 5.21 s(cAB)'70cr 5.32 5.32 5.32 5.32 5.32 S(CV083cf 4.72 4.72 4.72 4.72 4.72 S(CB)98cf 5.33 5.33 5.33 5.33 5.33 S(CB)99d" 5.40 5.40 5.40 5.40 5.40 S(CIl)l37u 4.87 4.67 4.87 4.87 4.87 S(CH)l38cf 4.83 4.83 4.83 4.83 4.63 S(CK)l39o' 4.72 4.72 4.72 4.72 4.72 S(HC)23$ b.35 5.35 5.35 5.35 5.35 S(HC)259 4.72 4.72 4.72 4.72 4.72 S(HV/)59$ 4.69 4.69 4.89 4.69 4.89 S(HW)60$ 4.80 4.80 4.80 4.80 4.80 S(3C)649 5.69 5.69 5.69 5.69 5.69 S(BC)66$ 10.16 10.96 7.44 16.32 8.88 S(BC)675 5.73 5.73 5.73 5.73 5.73 S(3C)69$ 5.35 5.35 5.35 5.35 5.35 s(c^v)e4$ 4.87 4.87 4.87 4.87 4.87 S(C\V)855 4.68 4.6P 4.68 4.68 4.6t; Average 5.322 5.360 5.192 5.615 5.26] Table Ila. Ilnze Learnint: by ITorraal Rata, Rat !f Pay 56 Day 57 Day 53 Day 59 Day 60 S(CW)28o' b.28 5.28 5.26 5.28 5.28 S(C\V)C9d' 5.16 5.16 5.16 5.15 5.16 S(BC)6:3d' 4.68 4.68 4.68 4.68 4.68 S(2C)63c? 5.21 5.21 5.21 - 5.21 5.21 S{C/EB)'?Od' 5.32 5.32 5.32 5.32 5.32 S(GW)83cf 4.72 4.72 4.72 4.72 4.72 8(03)98^ 5.33 5.33 5.33 5.33 5.33 3(03)990? 5.40 5.40 5.40 5.40 5.40 S(CH)l.57d' 4.67 4.87 4.87 4.87 4.87 S(CH)l38d' •1.63 4.83 4.83 4.83 4.63 S{CH)l39c? 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)259 4.72 4.72 4.72 4.72 4.72 S(:-IV/')S99 4.89 4.89 4.89 4.89 4.69 S(H\7)609 4.80 4.80 4.80 4.80 4.60 S(BC)64$ 5.69 5.69 5.69 5.69 5.69 S(BC)669 8.40 7,20 10.92 9.40 8.80 S(3C)679 5.73 5.73 5.73 5.^73 5.73 S(BC)699 5.35 5.35 5.35 5.35 5.35 S(CV/)84$ 4.87 4.87 4.87 4.87 4.87 S(CV/)859 4.68 4.68 4.68 4.68 4.68 Average 5.286 5.181 5.358 5.286 5.257 ?able IIu. L'aze Learning by IJormal Rat3. 65 Rat # Day 61 Day 62 Day 63 Day 64 Day 65 S(CW)28cr 5.28 J. 28 ■j.2b J. 1:8 J.^-b S(C\V)29cf 5.16 J. 15 5.16 5.16 5.16 S(BC)62cf 4.68 4.68 4.68 4.68 4.68 S(3C)63d' 5.21 5.21 5.21 - 5.21 5.21 S(C,/EB)70cf 5.32 5.32 5.32 5.32 5.32 S{CV/)83d' 4.72 4.72 4.72 4.72 4.72 S(CB)98cf 5.33 5.33 5.33 5.33 5.33 S(CB)99cf 5.40 5.40 5.40 5.40 5.40 S(ClOl37d" 4.87 4.87 4.87 4.87 4.87 S(CH)l38cf 4.83 4.83 4. 83 4.83 4.83 S(CH)l39c?" 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)25$ 4.72 4.72 4.72 4.72 4.72 S(HV;)59j 4.69 4.69 4.89 4.89 4.69 S(HV;)60$ 4.60 4.80 4.80 4.80 4.80 S(BC)649 5.69 5.69 5.69 5.69 5.69 S(BC)669 11.76 23.40 19.00 9.68 9.44 S{3C)67$ 5.73 5.73 5.73 5.73 5.73 S(BC)699 5.35 5.35 5.35 5.35 5.35 S(CW)84$ 4.87 4.87 4.87 4.87 4.87 S{CW)859 4.66 4.66 4.68 4.66 4.66 Average 5.398 5.952 5.743 5.200 5.288 Table Ila. ?.:aze Learning by !Tornal Rats. 66 Rat ,f Day 66 Day 67 Day 68 Day 69 Day 70 S{Gyf)288 Rat tl 76 ray 77 I'.iy 78 Day 79 Tiay 80 S(CW)28d' o,2b 0.28 5.28 5.28 5.28 S(CV7)29cf b.l6 5.16 5.16 5.16 5.16 3(EC)6Co 4.68 4.60 4.68 4.68 4.68 S(3C)63d' 5.21 5.21 5.21 • 5.21 5.21 SCC/EBl'^Od" 5 . 32 5.32 5.32 5.32 5.32 S(CW)83cr 4.72 4.72 4.72 4.72 4.72 S{CB)98o' b.33 5.33 5.33 5.33 0.33 S(Ci3)99J 5.40 5.40 5.40 5.40 5.40 S(CH)l37c? 4.87 4.87 4.87 4.87 4.87 S(CH)l38cf 4.83 4.83 4.83 4.83 4.83 S(CH)l39cf 4.72 4.72 4.72 4.72 4.72 S(HC)23$ 5.35 5.35 5.35 5.35 5.35 S(HC)252 4.72 4.72 4.72 4.72 4.72 S{Hs7)592 4.89 4.89 4.89 4.69 4.89 S(K',7)602 4.80 4.80 4.80 4.80 4.80 S (30)64$ ;;.69 5.69 5.69 5.69 5.69 S(BC)66$ 7.24 9.44 6.96 6.40 12.24 S(3C)679 5.73 5.73 5.73 5.73 5.73 S(BC)699 5.35 5.35 5.35 5.35 5.35 S(C.V)S4$ 4.87 4.87 4.87 4.87 4.87 S(CW)65$ 4.68 4.68 4.68 4.68 ^,.68 Average 5.183 5.288 5.170 5.143 5.421 Tatlc I la. IL.O.ZC Learninj^ by Ilorraal liats. by Rat # Day 81 Uay 82 Day 83 Day 84 Day 85 S{C\l)2&.28 S(CV;)29o^ .i.l6 5.16 5.16 5.16 5.16 S(BC)62c? 4.6y 4.68 4.68 4.68 4.68 5(30)63^? b.21 5.21 5.21 - 5.21 5.21 S{C/EB)'70.35 5.35 S(HC)255 4.72 4.72 4.72 4.72 4.72 S(:-W/)59$ 4.89 4. 39 4.89 4.89 4.89 s{ir,v)60$ 4.80 4.80 4.80 4.80 4.80 S(BC)64$ 5.69 5.69 5.69 5.69 5.69 S(3C)66$ 9.44 6.68 7.20 6.60 6.60 S(EC)679 5.73 5.73 5.73 5.73 5.73 S{BC)69$ 5.35 5.35 5.35 5.35 5.35 S(OT)849 4.87 4. 87 4.87 4.87 4.87 S(CW)85$ 4.68 4.68 4.68 4.68 4.68 Average K OOO 5.156 5.131 5.152 5.152 Table Ila. L.'aze Learning by TTorraal Rats, 71 Rat # ray 91 Day 92 Day 9?) Day 94 Day 95 s(cw)2acf 5.28 5.28 5.28 5.28 5.28 S(CW)29cr 5.16 5.16 5.16 5.16 5.16 5(30)62^? 4.68 4.68 4.68 4.68 4.66 slBOeso" 5.21 5.21 5.21 - 5.21 5.21 S(C,/EB)70cf 5.32 5.32 5.32 5.32 5.32 S(G\7)83d' 4.72 4.72 4.72 4.72 4.72 S(CB)98cf 5.33 5.33 5.33 5.33 5.33 S(CB)99d' 5.40 5.40 5.40 5.40 5.40 S(CH)l37o" ■'..67 4.87 4.87 4.87 4.87 S(CH)138J" 4.83 4.83 4.83 4.83 4.83 S{CH)l39cf 4.72 4.72 4.72 4.72 4.72 C(HC)235 5.35 5.35 5.35 5.35 5.35 S(HC)25$ 4.72 4.72 4.72 4.72 4.72 S(H\V)59$ 4.89 4.89 4.89 4.89 4.89 s(i-r;v')60$ 4.80 4.80 4.80 4.80 4.80 S(BC)64$ 5.69 5.69 5.69 5.69 5.69 S(BC)66$ 8.80 5.40 6.36 7,80 6.88 S(BC)67$ 5.73 5.73 5.73 5.73 5.73 S(i3C)69$ 5.35 5.35 5.35 5.35 5.35 S{CT/)84$ 4.87 4.87 4.87 4.67 4.87 S(-W)859 4.68 4.66 4.68 4.66 4.68 Averacre 5.^57 5.095 5.141 5.210 5.166 Table Ila. Llaze Learnirie; by llornal Rats, Rat # Lay 96 Lay 97 Lay 98 Lay 99 Lay 100 G(CW)':8o ■j.-^b 0.2H 0.2« ^.-^b o.lJb F(C\7)29d' 0.16 J. 16 5.16 I;. 16 5.16 S(3C)62J' •U68 4.68 4.68 4.68 4.68 S(EC)5?J' h.21 5.21 5.21 - 5.21 5.21 S(CAB)70d' 5.32 5.3? 5.32 5.32 5.32 SCCWJSSd' 4.72 4.72 4.72 4.72 4.72 S(CB)98cr 5.33 5.33 5.33 i;.33 5.33 S(CE)99J O.40 5.40 5.40 5.40 5.40 5(^)137^ 4.87 4.37 4.87 4.87 4.87 S(CH)l38d' 4.83 4.83 4.83 4.83 4.83 S(CH)l.39cf 4.72 4.72 4.72 4.72 4.72 S(HC)232 5.35 5.35 5.35 5.35 5.35 S(KC)25$ 4.72 4.72 4.72 4.72 4.72 S{HW)59$ 4.89 4.89 4.89 4.89 4.89 S(H\V)609 4.80 4.60 4.80 4.80 4.80 E(3C)649 ^.69 5.69 5.69 5.69 5.69 S(BC)669 7.96 6.52 5.88 7.32 7.92 S(3C)675 5.73 5.73 5.73 5.73 5.73 S(BC)695 5.35 5.35 5.35 5.35 5.35 S(CW)849 4.87 4.87 4.87 4.87 4.87 SlC^ffjSS^ 4.68 4.68 4.68 4.68 4.68 Avera£;e 5.217 5.149 5.1.18 5.187 5.215 T able Ila. ::aze Learn in ti Ly Lomal Rats. 7.-5 Failed Days required Rat -'' to learn. to learn. P(CW);3ec?' 12 S(CW)29c? 13 S(BC)62cr 16 Z{BC)6Zd- - 24 S(C/El;)70d^ 24 S((r//)83d' 21 S(CB)98cr 39 8(02)990^ 31 S(CE)l37rf 13 S(CH)l38c? 21 5(^)1390' 10 S(HC)239 24 S(HC)25$ 12 S(l-r.V)599 19 S(K\V)60$ 23 S(LC)649 31 5(EC)669 1 100+ S(BC)679 33 E(BC)699 23 S(CW)849 13 S(CV/)859 16 Total 1 : Average 27.67^ Tatle Ila. I'aze Learning by Tormal Rats. 74 yirat trial Rat # after 60 days' rest. S(CV/)28o 44.00 S(CW)29cr 23.80 8(BC)62d' 25.60 S(3C)63d' 23.20 S(cAB)70cf 64.60 S(CW)83d' 8.80 p(CB)98cJ' 72.40 ?(CE)99cr 108.40 Z{Cy.)i:y?d' 81.80 S(CK)l38t/ 9.20 S(CH)l39cf 15.80 S(KC)23$ 186.60 S(}IC)255 107.80 S(H\V)599 37.60 S(HY/)60$ 65.00 S(BC)64$ 42.20 S(BC)669 S(i;C)679 57.20 B(BC)69$ 188.20 S(CV0849 17.40 S(CW)859 15.20 Average 59.640 Tc-ible lib. Abrolutc Ketcr.ticn of Ilornal Rata. 75 Rat 7'^ ray 1 Day 2 Day 7^ Lay 4 Lay 5 C(CW)CSc? 23.40 7.44 7.40 6.28 7.00 3(0^)290" 9.40 5.36 11.08 5.08 i..08 S(BC)62d 19.84 5.56 6 . 32 4.88 ■..88 S(BC)63d- 12.68 5 . 52 b.52 - 5.52 5.52 S(C/ Inb. Avg. 195.36 180.55 1.71122 .52852 78.497 Nor, Avg. 191.00 171.41 1.74930 .52740 78.319 V/ater > Brain wt. Anatomical in cord in relation to Data /J body length. fa Brain v/t. Age in relation to killed body weight. Days. Inb. Avg, Nor. Avg, 71.723 71.666 .87685 .91745 .97052 1.05479 200. 186. Table III. Comparative Sunraary of Inbred and Normal Iiaz« Results. 88 Learning Day 1 Day 2 Day 3 Day 4 Day 5 6th Avg. 7th Avg. 541.423 512.149 73.343 127.526 79.997 44.486 37.449 43.480 30.014 16.674 Learning ray 6 Day 7 Day 8 Day 9 Day 10 6th Avg. 7th Avg. 24.457 11.131 16.371 8.954 10.646 11.891 10.486 8.154 9.789 8.989 Leai-nin^ Day 11 Day 12 Day 13 Day 14 Day 15 6th Avg. 7th Avg. 11.157 8.337 8.294 7.223 9.825 6.760 7.958 6.926 7.130 6.741 Learning Day 16 Day 17 Day 18 Day 19 Day 20 6th Avg. 7th Avg. 6.767 5.781 6.690 6.376 6.350 6.216 6.376 6.724 6.421 6.530 Learning Day 21 Day 22 Day 23 Day 24 Day 25 6th Avg. 7th Avg. 6.276 6.536 5.741 5.764 5.899 6.136 5.576 6.107 6.004 6.736 Learning Day 26 Day 27 Day 28 Day 29 Day 30 6th Avg. 7th Avg. 5.604 5.993 5.716 9.959 5.455 6.096 5.441 8.279 5.466 6.159 Learnin^j Day 31 Day 32 Day 33 Day 34 Day 35 6th Avg. 7th Avg. 5.320 5.513 5.674 5.776 5.594 5.919 5.658 6.936 5.464 6.267 Table IV. Coaiparative Gunuaary of 5th and 7th feneration Inbred l^aze Results. 89 Learning ray 36 Day 37 Day 38 Day 39 Day 40 6th Avj. 7th Avg. 5.406 5.959 5.444 5.541 5.284 5.913 5.316 5.987 5.230 7.073 Learning Day 41 Day 42 Day 43 Day 44 Day 45 6th Avg. 7th Avg. 5.399 6.124 5.853 6.227 5.396 6.101 5.261 6.056 5.461 29.444 Learning Day 46 Day 47 Day 48 Day 49 Day 50 6th Avg. 7th Avg. 5 . 364 9.473 5.259 11.684 5.361 9.084 5.396 6.347 5.387 6.747 Learning Day 51 Day 52 Day 53 Day 54 Day 55 6th Avg. 7th Avg. 5.713 6.107 5.447 5.673 5.230 5.599 5.244 5.759 5.647 5.827 Learning Day 56 Day 57 Day 58 Day 59 Day 60 5th Avg. 7th Avg. 5.336 7.101 5.359 6.204 5.301 5.770 5.210 6.444 5.241 9.736 Learning Day 61 Day 62 Day 63 Day 64 Day 65 6th Avg. 7th Avg. 5.333 14.376 5.366 8.593 5.312 7.907 5.198 5.879 5.209 6.639 Learning Day 66 Day 6 7 Day 63 Day 69 Day 70 5th Avg. 7th Avg. 5.198 7.244 5.264 6.364 5.186 5.953 5.286 6.890 5.166 5.856 Table IV. Comparative Summary of 6th and 7th Generation Inbred y.aze Results. 90 .earninc; Bay 71 Day 72 Day 73 Day 74 Lay 75 6th Avg. 7th Avg. 5.158 5.941 5.184 6.844 5.192 5.987 5.158 6.444 5.212 7.359 Learning Day 76 Day 77 Day 78 Day 79 Day 80 6th Avg. 7th Avg. 5.249 6.559 5.189 7.016 5.209 7.033 5.269 6.341 5.169 5.959 Learning Day 81 Day 82 Day 83 Day 84 Day 85 6th Avg. 7th Avg. 5.155 7.976 5.149 11.707 5.158 5.821 5.158 6.290 5.158 8.730 Learning Day 86 Day 87 Day 88 Day 89 Day 90 6th Avg. 7th Avg. 5.158 6.170 5.158 5.633 5.158 6.364 5.158 5.947 5.158 11.553 Learning Day 91 Day 92 Day 93 Day 94 Day 95 6th Avg. 7th Avg. 5.158 7.170 5.158 10.730 5.158 8.296 5.158 7.719 5.158 6.353 Learning Day 96 Day 97 Day 98 Day 99 Day 100 6th Avg. 7th Avg. 5.158 7.364 5.156 6.679 5.158 7.736 5.158 7.604 5.158 7.559 Failed to learn. Days t( 3 required 3 learn. Absolute retention. 6th Avg. 7th Avg. 0 2 32.93 44.00t 65 126 .443 .680 Table IV. Comparative Summary of 6th and 7th Generation Inbred Maze Results. 91 Kelearninti Day 1 Day 2 Day 3 Day 4 Day 5 6 th Avti. 7th Avg. 31.866 45.352 10.357 17.392 11.043 7.344 9.009 11.104 6.071 6.064 Relearning Day 6 Day 7 Day 8 Day 9 Day 10 6th Avg. 7th Avg. 8.174 6.264 7.426 8.312 6.351 7.456 6.111 6.584 6.129 7.936 Relearning Day 11 Day 12 Day 13 Day 14 Day 15 6th Avg. 7th Avg. 6.163 6.304 6.054 5.720 5.886 6.576 5.660 5.656 5.563 0.656 Kelearning Day 16 Day 17 Day 18 Day 19 Day 20 6th Avg. 7th Avg. 5.628 0.656 5.674 0.656 5.689 0.656 6.163 ;3.656 5.740 6.656 RelearniriK Day 21 Day 22 Day 23 Day 24 Day 25 6th Avg. 7th Avg. G.1S6 5.656 5.897 L) . 6 o 5 5.911 0.606 6.206 5.656 5.811 ^.606 Relearning Day 26 Day 27 Day 28 Day 29 Day 30 6 th AVti. 7th Avg. 6.349 5.Gj6 5.711 o.6b6 6.006 b.656 5.909 5.656 5.874 5.656 Relearning Day 31 Day 32 Day 33 Day 34 Lay 35 6th Avg. 7th Avg. 5.989 0.656 5.994 5.634 5.656 5.914 5.656 6.040 5.606 Table IV. Comparative ouraaary of 6th and 7th Generation Inbred Maze Results. 92 Relearnint^ Day 36 Day 37 Day 38 Day 39 Day 40 6th Avg. 7th Avg. 6.014 L. 6'j6 G.063 5.991 .,.6L)t- 5.806 J . '3 b t; 5.751 0.6 5D Relearning Day 41 Day 42 Day 43 Day 44 Day 45 6th Avg. 7th Avg. 5.657 5. 6o6 5.917 b.obG 5.823 5.656 5.777 O.G56 5.934 5.656 Rel earning Day 46 Day 47 Day 48 Day 49 Day 50 6th Avg. 7th Avg. 6.166 5.656 5.871 5.656 6.014 5.6D6 5.600 5.656 5.711 5.656 Failed to relearn. Days to required relearn. 6th Avg. 7th Avg. 2 0 14.14t 8.60 Body Body Brain Anatomical length weight weight Data in ran. m grras. in grms Cord Water weight in brain in grms. > 6th Avg. 200.71 195.04 1.75234 .53881 78.49 7th Avg. 184.71 152.47 1.63286 .50794 78.51 ■..'ater ,. Brain wt. > Brain wt. Age Anato-iicHl in cord in relation to in relation to killed, Data ,j body length. body weight. Days. 6th Avg. 7th Avk. 71.73 71.70 67413 68219 .91653 1.07051 196. 207. Table IV. Comparative Sumnury of 6th and 7th Generation Inbred Uaze Results. 93 Learninii; Dixy 1 DMy 2 Day 3 Day 4 Day 5 ror. B T:xcept B 849.458 248.380 187.729 52.997 88.511 :^.7.857 36.160 15.085 ;29.6d9 ::2.557 Learniriii Day 6 Day 7 Day 8 Day 9 Day 10 i:or. B Except B CO. 093 15.320 15.822 11.550 13.066 11.223 10.276 14.063 12.964 7.110 Learniriji Day 11 Day 12 Day 13 Day 14 Day 15 IJor. B Except 3 8.142 6.652 9.544 6.393 8.907 6.190 7.476 6.475 9.289 5.768 Learning Day 16 Day 17 Day 18 Day 19 Lay 20 Nor. B Except B 6.702 6.675 7.822 5.382 7.067 5.025 7.467 5.265 7.040 4.959 Learning Day 21 Day 22 Lay 23 Day 24 Day 25 !Tor. B "xcept B 6.529 4.956 6.973 4.948 6.804 4.868 6.719 4.892 6.102 4.908 Learning Day 26 Lay 27 Lay 28 Day 29 Day 30 Nor. B Except B 6.031 ^.908 6.156 4.908 5.240 4.908 6.280 4.908 6.142 Learninfi Day 31 Day 32 Day 33 Day 34 Day 35 llor. B l^xcept 3 6.756 4.906 6.294 4.908 6.006 4.908 6.267 4.908 5.842 4.908 Table V. Comparative Gunrnary of B Strain ana normals Lackinti B ::ar.e Kesults. 94 Learning Day 36 Uay 37 Day 38 Day 39 Day 40 Nor. B Except 3 b.758 -:.908 b.704 4.908 b.587 4.908 0.971 4.908 b.861 4.9 08 Learning Day 41 Day 42 Day 43 Day 44 Day 45 Nor. B Except B 5.923 •1.908 6.461 4.908 5.999 4.908 5.706 4.908 6.159 4.908 Learning Day 46 Day 47 Day 48 Day 49 Day 50 llor. B Except B 5.781 4.908 5.501 4.908 5.466 4.908 5.586 4.908 5.643 4.908 Learning Day 51 Day 52 Day 53 Day 54 Day 55 llor. B Except B 5.874 4.906 5.963 4.908 5.572 4.906 6.559 4.908 5.732 4.908 Learning Lay 56 Day 57 Day 58 Day 59 Day 60 Nor. B Except 3 5.679 4.908 5.546 4.906 5.959 4.90b 5.690 4.908 5.723 •..9 06 Learning; Day 61 Day 62 Day 63 Day 64 Day 65 llor. B Except B 6.05.? 4.906 7.346 4.908 6.857 4.908 5.821 4.908 5.794 Learning Day 66 Day 67 Day 68 Day 69 Day 70 !'or. B Except B 5.928 4.906 5.914 4.9 08 5.528 4.908 5.963 4.908 5.643 4.90tj Table V. Comparative Surnnary of B Strain and ITorraals Lacking 3 liaze Keaults. 9b Learniriii lay 71 Day 12 Day 73 Day 74 Day 75 Nor. B Except B 5.692 •i.yOb 5.519 5.426 4 .y06 5.603 5.361 4 .'VJii Learnint^ Day 76 Day 77 Day 78 Day 79 Day 80 Nor. B Except B 5.550 •..908 5.794 4.908 5.519 4.908 5.457 4.90b 6.106 4.9 06 Learning Day 81 Day 82 Day 83 Day 84 Day 85 llor. B Fxcept 3 5.746 •1.908 5.673 4.906 5.617 4.908 5.608 4.906 5.497 4.908 Learning Day 86 Day 87 Day 88 Day 89 Day 90 ITor. B Except B 5.794 4.908 5.488 4.908 5.546 4.908 5.479 4.906 5.479 4.908 Learning Day 91 Day 92 Day 93 Day 94 Day 95 Nor. B Except B 5.723 4.908 5.346 4.906 5.452 4.y06 5.612 4.906 5.510 4.908 Learninf^ Day 96 Day 97 Day 98 Day 99 Day 100 IJor. B Except 3 5.630 4.908 5.470 4 . y06 5.399 4.yOc 5.559 4 . yOo 5.626 t .90S Failed to learn Days tc 1 required > learn. Absolute retention. Nor. 3 Except 3 1 0 35.67+ 16.42 72 51 .475 .083 Table V. Comparative Gunrnary of ^ Strain and u'orraalB Lacking B Llaze Results. Relearnini^ Day 1 Day 2 Day 3 Day 4 Day 5 Nor. B Except 3 36.215 23.480 29.230 11.767 10.930 8.597 11.180 5.873 7.990 5.587 Rel earning Day 6 Day 7 Day 8 Day 9 Day 10 ITor. B Except B 8.075 6.410 7.200 5.307 6.970 5.223 6.340 b.223 6.240 5.223 Relearning Day 11 Day 12 Day 13 Day 14 Day 15 Nor. 3 Except B 5.935 b.223 5.750 5.223 5.740 b.223 5.700 5.223 5.835 5.223 RelearninK Day 16 Day 17 Day 18 Day 19 Day 20 i:or. B Except B 7.090 b.223 5.725 5.223 5.890 b.223 5.550 b.223 5.765 5.223 Relearning Day 21 Day 22 Day 23 Day 24 Day 25 to Nor. B Except B 6.200 b.223 5.415 b.223 b.415 0.-323 b.415 b.223 b.415 5.223 Failed to relearn. Days to required relearn. ITor. 3 Except B 0 0 8.24 4.08 Table V. Coraparative Suinraary of B Strain and Normals Lackinti B i:aze Results. 97 Anatomical rata j'ody lent^th in mn. Body Brain Cord weifcjht weiejht weitjht in grns. in grms. in grns. Water in brain llor. 3 Except P 193.00 189.50 175.73 l.'?537& .54191 166. Irt 1.75426 .51646 78.25 78.37 Anatomical Data Water in cord > Brain wt. < Brain wt. in relation to in relation to body length. body weight. Age killed. Bays. Nor. B Except B 71.46 71.61 .90406 1.02303 .92746 1.07861 200. 175. Table V. Conparative Sunrnary of B Strain and irornals Lacking B. I-Iaze Results, 98 The luatson VCla^e. Plate I. 99 100 i2 t/-»^D II -IS /- 1 n I - « Mill J- 4 7- ■ -U /j-'v _X1 //-/t n - 'f /»-i» IS -It. 3 17 -if 31 -U t fi. ..H.fe- g E g g fe « " * 1 103 IV. EXPEhlL'LFNT 2: THJ' PKhJLIUINABY IKCLIIffil PLi\IIE . The apparatus used in tiais experiment (see PlHte VI) wp.s desij^neri especially to nake a problem exceptionally difficult to learn, and in this purpose it succeeded beyond expectation. The basic principle in the same as thwt of the apparatus used by V/ataon^in his experimrnts at the Univei-si- ty of Chicdi^o , described and illustrated in his monograph "An- imal Education," page 37. But my apparatus differs from his in several respects. V/atson, Animal Education, Chicago, ]903. Plate VI shows in detail the construction and meth- od of operation. The food box. A, is framed of v/ood, 11 x 12 inches base, 11 inches in heijjht and covered by 3/6 inch heavy v/ire mesh. It is fitted v/ith a hard rubber aoor, d, 3/16 Inch thick, 5 inches high and 4 1/4 inches wide. To the door is fastened a cord which passes over a pulley, p, and is \7eight- ed at the other end with a piece of lead, 1, of sufficient Vr-eight to insure the openint^ of the aoor upon releasing the latch. B shows the device for latchint^ and releasing the door. A short distance above the door is fastened a 3inch electric- al magnet, m; directly belov/ that is a steel wire, s.w. , sur- mounted by a steel disk, s.d., of the same diajneter. as the core of the mat^net. The steel wire holds the door by dropping through holes in two brass plates, g, which serve os guides, to a point, behind another brnss plnte which is set at the top of and behind the door, 1 1/2 i.u'i uelow the top of the door. 104 The setscrew, s.b., placed on the wire above the lov;ei' (^xiicie prevents any further di'op. V.Qien the steel v/ire holda the door the dirk is 2nM. below the naj-^net; when tiie disk is drnv/n up to the matinet, l/2inn. clearnnce is allowed for the door. Pack of the feeding box A, is placea the inclined plane, J. .P. The inclined plane has a hard rubber base ?^/B inch thick, 6 incites long and 2 3/6 inches wide. Upon standards at the middle of the base I'ests the plane itself. The plane is of wood fibre and of the seixne dimensions as the ba.se. The plane is weighted at the end nearest the box in order to in- sure its return to position iifter use. At the end opposite the weight, platinum electrical contacts, e.c, are placed in both base and plane. The power is provided through wires connecting with the regular electric lighting system, direct current, 115 volts. A 32 c.p. laiJip is placed in the series in order to avoid any danger of short-circuiting. In order to make the contact and allow the current to pass through the magnet, thus raising the steel wire and releasing the door, it is necessary for the rat to step on the point of operation, 0, which lies well out toward the end of the plane. Cn account of a certain amount of latency in the operation of the magnet, the rat must not only make the contacts touch, but must also inhibit furtlier action, remctining on point o until the click of the disk meeting the magnet is heard. Over the food box and plane is placed a cage constructed of 1/2 inch heavy wire nesh, the base measurements of which are 24 x 24 inches and the height 14 inches. This allows the rat ample room to explore on all sides and above the food box. V.'hen the rat is within the entrance, e, to the cafc,e is closed. The preliminary inclined plane experiment was not intended so much as a decisive experiment as tio test the ef- 100 ficiency of the apparatus. The resultn, however, are Bi^nifi- cnnt and, therefore, included here. The object of the experiment v/as to have each rat learn to reach the interior of the food box from the entrance to the cat,e in the least posnible time. The proceciure of a perfectly trained rat v/as, to run from the entrance, e, to the point of operation, o, reraainine, there until the click of the disk against the ma^^net insured the door being open, then run- ninji, through the door of the box to the food which was placed v.'ithin at point f. The starting time was taken when the ani- mal entered at e, another v/hen the magnet clicked, and the finfil time when the food box v;as entered. The object of tak- ing/ the two times was that differences in association betv/een the inbred series and the control mi^^ht be compared. But as in both series the association v/as practically perfect after the second day such comjiarison is useless. In preparation, each animal, beginning at the age of sixty-five days, was fed alone in the food box ten minutes daily for five consecutive days. During this period the door of the food uox v/as allowed to remain open, thus giving the rat an opportunity to become acquainted with all parts of the interior of both box and cage. At the age of seventy days the experiment be^^an. Bix males and five females fi-om the inbred strain were used and, as control, an equal number of males and females from the normal series. All the inbred rata were from the 6th generation. The stimulus used was their regular food, bread soaked in milk. rt.s one of the first rats used took fourteen hours before his first accidental success, it v:as decided to use "cumulative" time for the first few trials. By this method each rat was allowed to v/ork thirty minutes and then, if un- 106 successful, he v'as taken out wliile tlie door was oi)ened, and he wag then returned to feed for five minutes and used no more that day. V.lien they bej^an to succeed within the half }iour, each rat was required to open and enter the food box five tinieo each day. At the end of the fifth trial it was allowed to feed for five iriinutes, but pei-nitted no nore food until the conple- tion of the next day's experiment. Fach tat was used daily foi- tv/enty days. As a tine limit had been placed, no criterjon of perfect learning v/as establiphed for this experiment. At the conclusion of the learnint: experiment the rats v^iere fed in the runway which has already been described for sixty days. At the end of this period they v;ere tested for retention, and were worked for five days in order to asoertfin the effects of the previous training. The results of the experiment for the inbred rats are given in tables Via, VIb , and Vic; for the normal control series in tables Vila, Vllb, and VIIc. These tables ^iye only the averages of the five daily trials of individual rats. Ta- bles Via and Vila show, respectively, the daily averat:e time in seconds of the inbred and normal control series during the process of forming the inclined plane habit. The time includ- es both opening the door at the plane and entering the food c ox . Tables VIb and Vllb show the absolute retention of the inbred and normal control series respectively. These ta- bles show the absolute retention of the normal control series to be stronger than than that of the inbrnd. Tables VIc and VIIc serve only to show individual daily averages during the five days of testing for tiie effects of previous training. The inoividuril anatomical data, can with the above be better treatea in the comparative summariefl. 107 Tab.le VIl.T prpMentp a comp'irMtlve aunnury oonHiBtinti cf the dalJy Hveraj/es of nil the inbred and all the control rats. Ti'rom thii=< table are constructed the comi^arjitive ourvef? cf lenrnint,. Erom the eleventh day the f.lgureR for learnjnt; time of the normal ratp are lern than thoBe of the inbred s. The absolute retention of the normals iB stroni^er than that of the inba-.eds. In the five trials to tent the effects of pre- vious traininti the time of the norinaly is less each day than that of the inbred rats. In these criteria of ability the rats of the normal control series are shown, on the average, to be superior to those of the inbred aeries. Body length of the inbred rats used in the preliminary inclined plane is, on the avera^^e, slightly greater than is the case with the norrasils; body weit;ht, however, is a trifle less. The average actual brain weig}it of the inbreds is leas than that of the^ normals. The relative brain weight (in reference to body lent^th) of the inbreds 1p 11.61,"? less than that of the normals. The relative brain weight (in reference to body weight) of the inbreds is ll,fir\'.' less than that of the normals. Although killed at a later at^e, the percentage of water in brain and cord of the InKreds is great- er thfn is the case with the normals. The tables of comparative summaries of preliminary inclined plane results support the hypothesis that the deter- ioration of brain weight in a strain of rate is accompanied by deterioration in the ability to form habits. In Plate VII is shown the curve of learnJnii (left) and of relearnin^i (right) of the inbred rntH compared with thosp of the normnl control. The inbred curve if shown by the solid line, that of the control by the broken line. The ordi- nates give the time in secondn, and the abBciflsae the number 106 of the day in which such time vjus made. Both leurninti curvefi are iri'etn.ilHr, but on the eleventh day that of the control series passes permanently below that of the inbred, '"he curv- es of relearnint: show that the inbreds had failed to benefit by practice to so ^reat an extent as the normal control. 109 Rat -^ Rat # Day 1 Day Day 3 Day 4 Day 6 Day 7 Day 8 Day 9 Lay 5 6E82d" 2166.68 1032.08 25.28 21.76 13.12 6E83cf 1721.;56 1511.68 129.32 15.04 9.00 6B84c^ 488.44 151. D 2 57.76 1 3 . ] 2 13.96 6B85cr 3022.24 7067.24 26.68 15.96 16.24 6287$ 392.00 105.24 16.68 24.04 26.56 6B88$ 3424.56 720.40 42.72 47.52 8.44 61389$ 3787.04 5444.32 15.64 25.92 4.92 6B50$ 4722.96 297.76 65.64 33.84 133.16 6B51$ 636.00 932.64 122.40 233. ]6 4.20 eAeid" 394.04 267.20 40.12 53.08 72.4^ 6A62d' 869.12 413.28 119.08 21.64 7.24 Average 1965.858 1631.178 60.302 45.916 28.116 Day 10 eE82c' 5.00 3.48 3.24 4.40 6.56 eEesd' 9.80 12.72 7.76 5.00 5.24 6E84cf 5.64 15.04 4.48 17.80 6.20 6B85d" 15.68 6.40 4.80 12.36 4.92 6B879 10.28 8.20 18.52 5.76 9.32 6B88$ 20.48 8.12 16.08 8.48 6.04 6B89$ 5.80 5.24 9.52 10.00 4.76 6B50$ 13.44 4.56 13.32 6.04 5.46 6B515 3.60 66.20 4.80 5.64 8.28 6A61cf 28.08 25.52 11.48 5.44 16. ^76 6A62d' 4 .52 6.68 6.04 104.28 4.64 Average 11.120 14.833 0.095 16.855 7.109 Table Via. Prelinin^^.ry Inclined Plane Learnint; 110 Rat ^f Day 11 Lay 12 Day 13 Lay 14 Lay 15 eE82cf 5.16 7.88 8.60 11.68 7.28 6383cf 4.66 6.00 10.40 9.00 8.64 6Be4d' 5.56 9.60 5.68 22.16 33.72 SBSbd 8.68 8.16 9.36 -8.84 7.00 6Be7$ 5.24 24.60 7.40 5.64 4.92 6Bee$ ?.56 6.32 10.88 33.24 12.04 6B89$ 4.40 4.04 5.24 4.64 16.76 6B50$ 12.36 19.92 4.80 5.44 5.48 6B51$ 3.40 4.76 3.68 3.96 5. ''2 6A61C' 5.40 6.28 8.96 9.72 6.96 6A62C? 10.44 6.56 9.24 5.76 4.68 Average 6.262 9.465 7.658 10.916 10.291 Rat # Bay 16 Day 17 Bay 18 Bay 19 Bay 20 eE82d" 10.08 5.60 4.96 5.00 4.84 eBSSd" 3.12 6.16 7.36 3.68 21.44 eBBAcf 8.76 6.08 6.04 7.96 29.40 6Be5cf 6.28 10.92 3.36 3.56 10.12 6E879 3.64 3.16 3.60 11.08 7.52 6E88$ 8.28 5.04 5.96 3.68 £.28 6B89$ 3.64 4.40 3.36 4.68 5.52 6B509 6.88 5.48 10.60 27.20 8.44 6B519 6.00 4.72 4.88 17.24 3.68 6A61d' 19.60 8.24 3.28 6.36 5.48 eAeed* 4.48 6 . 92 7.44 6.48 S.04 Average 7.360 6.247 5.531 8.811 10.251 'able Via. Preliminary Inclined Ilane Learning ]1] Rat // First trial ifter 60 days' rest. 6E82cf 6Be?cf 6B84d' eBBbd 6E87$ 6B8£$ 6B89$ 6250$ 6B51$ 6A61d" 6A62cr 18.20 7.80 215.20 162.20 17.40 37.80 7.60 14.40 148.80 6.80 16.20 Average 59.309 ible Vlb. Absolute Retention of Inbred Rati Preliminary Inclined Plane. 112 Rat 'i Lay 1 Day Day 3 Day 4 Day 5 6B82cf 7.00 13.24 4.64 6.'72 6.60 6ii83cr 7.96 5.06 6.]6 9.92 7.84 6B84d' 74.16 7.16 4.]6 3.32 2.96 6B85cf 36.92 11.12 22.84 1-8.08 8.64 6B87$ ll.fiO 6.72 6.72 10.96 17.84 6B889 16.44 8.92 17.20 5.40 6.08 6B£9$ 6.36 4.56 2.76 3.96 3.60 6B5O9 22. ao 19.60 21 .92 12.32 12.76 61^519 34.48 18.44 13.40 8.24 8.72 6A61cr 10.12 7.56 9.28 6.]6 3.80 6A62d' 39.48 14.08 17.60 4.76 7.72 Average 24.302 9.905 11.516 8.349 7.869 'able Vic. Preliminary Inclined Plane Relearning by Inbred Rats. Kat .9 Body length in nri. Body weight in grms. Brain weight in t;rrna . cord weight in time. water in brain 6B82cr 194. 178.0 1.6737 .5207 77.98 6B83cr 198. 199.4 1.6951 .4771 79.01 6B840- 200. 194.6 1.6707 .5048 78.37 6B85o" 192. 170.4 1.6110 .4846 78.00 6B87$ 189. 156.2 1.7264 .4980 78.48 6B889 169. 157.2 1.3144 .3753 76.67 6B895 187. 151.3 1.6407 .4591 78.56 6E5O9 189. 146.9 1.6710 .4777 79.00 6B51$ 189. 154.4 1.7077 .4881 78.93 eAeitf 192. 171.0 1.6109 .4947 78.69 6A62^^ 180. 151.9 1.5048 .4487 78.52 Averafe^e 190.82 166.50 1.62031 .47535 78.565 113 Rat # Water in cord ,^ Brain wt. in relation to body length. ;:^ Brain v/t. in relation to body weight. Age killed. Days. 6Be2c? 70.02 .86273 .94028 203. 62830- 72.21 .85611 .85010 203. 6E84d' 70.68 .63535 .85765 203. 6E85cf 70.64 .83906 .94542 203. 6Ee7$ 71.00 .91344 1.10525 203. 6E68$ 71.49 .69544 .83613 203. 6E69$ 71.27 .87738 1.08440 203. 6E50$ 72.30 .88413 1.13750 181. 6B51$ 72.44 .90355 1.10602 lei. 6A61C?' 71.96 .63901 .94205 177. 6A62cr 71. '79 .83600 .99065 177. LV I'orraal Lata. 114 Eat # ray 1 Day 2 Day 3 Day 4 Day 5 G(C)2$ i:jb3.32 3082.84 4 7.80 24.72 14.44 £(C)3$ 801.68 193.32 41.92 35.92 10.76 i:(C)4$ 6664.36 74.72 36.60 17.64 5.72 8(C)5tf 471.28 412.84 37.80 25.60 28.20 S(C)6cr 5085.76 497.36 56.36 25.00 5.64 S(C)7cf 595.44 649.60 186.12 31.40 68.76 E(C)8c/ 839.24 3188.76 139.88 15.40 7.48 S(C)99 6 502.40 986.12 S4.60 30.68 8.32 S(C)109 34 22.72 25.32 21.64 19.28 19.56 S(HC)iyd' 909.32 1321.00 136.24 13.32 18.84 SlHCJaOcT 528.80 250.24 88.56 66.04 52.72 Average 2470.393 971.102 79.775 27.564 21.840 Rat # Day 6 Day 7 Day 8 Day 9 Day 10 C{C)25 40.96 28.20 14.16 16.04 14.60 S(C)3$ 8.48 4.84 10.36 10.12 9.16 S(C)4$ 6.80 8.20 12.52 11.20 5.44 r(c)5o' 17.28 5.80 4.04 5.28 3.24 E(C)6d" 12. 72 7.44 13.92 12.80 12.28 2 ( C ) 7cf 35.44 11.68 8.44 8.20 3.24 8(C)8(^ 16.04 10.24 7.08 5.36 12.32 S(C)9$ 32.92 8.68 8.60 9.08 14.24 ?(C)10$ 15.20 8.80 6.92 6.80 4.96 S(HC)l9c? 17.64 8.28 10.72 7.84 4.80 C(HC)20d" 19.88 11.96 11.80 5.96 4.36 Average 20.305 10.375 9. 869 8.971 8.058 fable Vila. Prelininary Inclined Plane Learning cy Normal P.ats. 115 Rat # Lay 11 Lay 12 Lay 13 Lay 14 Lay 15 C(C)C9 4.60 3.96 4.92 6.44 11.36 ?(C)3$ 4.68 5.88 3.32 3.08 3.56 S(C)4$ 7.48 4.68 5.20 5.36 5.56 S(C)5cf 3.40 3.48 3.84 1.92 2.28 8(C)6d' 7.76 7.08 G.92 3.08 3.76 S ( C ) 7c? 8.64 5.68 3.88 2.96 2.20 S(C)Sd' 5.84 4.12 11.76 7.08 8.16 S(C)9$ 4.92 6.08 5.56 5.00 3.28 S(C)10$ 2.64 6.48 2.64 4.40 2.48 S{KC)l9a^ 5.52 4.92 4.12 5.36 4.00 S(KC)20o 3.08 2 . 80 3.44 4.00 3.00 Average 5.342 5.015 5.055 4.425 4.513 Rat # Lay 16 I-ay 17 Lay 18 Lay 19 Lay 20 C(C)29 7. OS 5.28 9.76 19.96 16.16 S(C)39 10.40 6.20 4.36 4.72 4.92 S(C)49 9.32 4.36 4.40 8.44 5.76 G(C)5d" 2.44 1.84 2.56 3.20 2.28 S(C)6cf 5.15 5.00 6.20 4.72 3.88 S(C)7cf 2.16 2.28 2.44 2.64 2.12 C(C)8cJ 2 9*^ 2.68 2.40 2.36 2.52 G(C)99 3.20 2.60 6.76 3.28 3.68 S{C)109 2.16 4.44 5.04 4.20 4.64 C(HC)19C- 8.80 5.72 5.08 4.56 8. SO C(}:c)20d" 2.04 2.60 3.80 5.88 7.08 Averat;e 5.062 3.727 4.800 5.615 5.622 Table Vila. Preliminary Inclined Plane Learninj^ by ITornal I>at,fl. 116 First trial Rat -^ after CO day's rent. C(C)29 6.80 S(C)3$ 17.80 S(C)4$ 31.20 C(C)5J- 12.00 8(0)60- 61.80 £(C)7d' 34.80 £(0)80* 15.20 S(C)99 8.80 S(C)109 331.00 S(HC)l9d' 8.80 C(i:C)20o" 12.60 Average 49.164 Table Vllb . Absolute Retention of Hormal Kate. Prelimingry Inclined Plane. n 7 Rat # Lay 1 Day 2 Day 3 Cay 4 Day 5 G(C)29 4.32 4.80 3.96 2.32 '1.68 S(C)39 12.64 b.36 2.48 2.68 13.04 S(C)49 c.oe 2.80 3.64 5.60 6.40 S(C)5cf 5.20 2.72 1.80 -2.40 1.64 S(C)6cr 16.88 5.20 6.04 5.48 4.48 5(0)70^ 12.84 3.12 2.48 2.68 J. 92 S(C)8cf 9.44 4.32 6.80 5.32 4.16 S(C)9$ 12.20 8.44 6.52 7.36 5.52 S(C)109 96.52 13.24 21.76 3.60 19.52 S(HC)l9cf 3.96 5.28 4.56 5.84 3.44 £(HC)20cf 6.04 5.20 4.52 3.60 4.16 Average 17.102 5.498 5.869 4.262 6.651 :able YIIc. Prelirninciry Inclined Plane Belearnini^ by rorinal Rats. Rat If Lody length in nin. Pody weight in grme. Brain weight in grias. Cord weight in grns. Water in brain S(C)29 179. 142.6 1.7851 .4877 77.83 S(C)39 187. 152.0 1.8488 .5461 78.08 S(C)49 179. 147.1 1.7656 .5087 76.15 8(0)5^ ibb. lb9.5 1.7498 .5061 77.91 S(C)6tf 197. 185.2 2.0237 .5890 78.14 S(C)7c? 192. 161.5 1.7990 .4996 78.10 s(c)scr 206. 199.4 1.8975 .5454 77.80 S(C)9$ 183. 158.4 1.7390 .4970 77.94 £.(0)109 193. 197.0 1.8230 .5575 78.10 S(HC)l9d' 197. 198.2 1.S392 .5599 78.37 S(KC)20d' 166. 148.0 1.7432 . 5129 77.38 Average 1£9.45 168.06 1.81946 .52819 77.982 118 \7ater ;? Brain v/t. :\' Brain \vt. Age in cord in relation to in relation to killed, Rat 5 body length. uody weight. lays S(C)29 71 . 38 .99726 1.25182 167. E(C)39 71.05 .98866 1.21632 167. S(C)49 71.59 .98648 1.20041 167. S ( C ) 5cf 71.49 .94584 1.09705 160. S(C)6cf 71.17 1.02726 1.09271 183. S(C)7cf 71.43 .93696 1.31393 160. S(C)8d' 70. ]0 .92112 .95160 183. S(C)99 71.35 .95027 1.09765 180. S(C)109 71.17 .944 56 .92538 180. s(i:c)i9cf 71.35 .93360 .92795 164. S(HC)20cf 70.33 .03720 1.1 7784 164. 119 Learning, Day 1 Day 2 Day 3 Day 4 Day 5 Inb. Avg. Nor. Avg. 1965.858 2470.393 1631. ]78 971.102 50.302 79.775 45.916 27.564 28.3 16 21.840 Learning Day 6 Day 7 Day 8 Day 9 Day 10 Inb. Avg. Y.OT. Avg. 11.120 20.305 14.833 10.375 9.095 9.869 16.855 8.971 7.109 8.058 Learning Day 11 Day 12 Day 13 Lay 14 Day 15 Inb. Avg. Nor. Avg. 6.262 5.342 9.465 5.015 7.658 5.055 10.916 4.425 10.291 4.513 Learning Day 16 Day 17 Day 16 Day 19 Day 20 Inb. Avg. Nor. Avg. 7.360 5.062 6.247 3.727 5.531 4.800 8.811 5.815 10.251 5.622 Absolute retention, Inb. Avg. Nor. ^vz^ 59.309 49.154 Relearning Day 1 Day 2 Day 3 Day 4 Day 5 Inb. Avg. Nor. AVt^. 24.302 17.102 9.905 11.516 5.498 5.669 8.149 4.262 7.869 6.651 'able VIII. CoiapiirMtive Summary of Inbred and Normal Inclined Plane (Preli::.innry ) Results. l^JO Anatoriicol Data Pody lent^th in mra. Body weight in tjrme. Brain weight in grme. Cord weight in grms. Water in brp.in Inb. Avtj. !'or. Avg. 190.82 189.45 166.50 168.08 1.62031 1.81946 .47535 .52819 78.^65 77.982 Anatomical rata Vt'ater in cord fo Brain wt. n' in relation to in body length. bi Brain wt. relation to ody weight. Age killed. Days. Infc. Av^. Nor. Avg. 71.436 71.] 28 .84929 .96084 .98140 1.09571 194. 170. Table VIII. Comparative Cunrnai'y of Inbred ynd Norrnal Preliminary Inclined Plane Results. 122 5-S-.£__s_e_S- .» • r^ i I p 3 123 V. K/J^EKILI'lNT 3: THE IlICLIIffiU PLAlO*;. The apparatus used in thiH experiment was the seme ae that used in Txperiinent 2: the Ineliminary Inclined Fltme. The animals were prepared in the same way as for the previous experiment, and began work at the ati;e of seventy days. Sixteen males and fourteen females from the inbred strain were used and, as control, an equal number of males and females from the normal series. Of the inbred rats, fifteen v/ere from the 7th generation, fourteen from the 8th and one from the ninth. As the behavior of the sinc^le ninth generation rat was no worse than the average of the Sth her results have been induced in the tables and curves of the 8th generation. The stimulus used in this experiment was bread eoaked in milk. Cumulative time v/as used in the earlier trials as in the previous experiment, \7hen the rats be^n to succeed within the half hour, each rat was required to open and enter the food box three times each day. At the end of the third trial it was allowed to feed in the box for five minutes, but was permitted no more food until the completion of the next day's experiment. Each rat was used daiDy until it had learn- ed the problem perfectly, the criterion of perfection being three perfect trials for each of three succesr,ive days. A per- fect trial consisted in rijnning from the entrance to the point of operation on the plane at the rear of the box, opening the door, runninik around and entering the box, all v/ithin four seconds; but, if the time consumed in opening the box after passing the entrance was more than two seconds, or, if the time consumed in entering the box after having opened the door T/ae more than tv/o seconds, the trial was considered a fai3ure. 1?A It was possible for n rat to have a perfect trial in four hpc- ondP, or a failure in a less total tine. Those rate failint^ to learn within one hundred days (300 trials) v/ere no longer used foi- experimentation. Those rnts learnini^ the inclined plcine v/ere, at the conclusion of the experiment, fed for six- ty days in the runway. At the end of this period they v/ere tested for I'etention and releti.rning. Three of the rats formed the habit of 1 if tin^^ the plane at the end nearest the box and thus formin^i the contact, but it apparently affected neither the rapidity of each trial nor the number of days required for perfect learning. One of the normal rats plaxed his nose between the electrical contacts and received a shock, but beyond one squeal and a vigorous rubbing, of his nose, he showed no sit;n of harm and had apparent- ly forgotten the experience the next day. Some of the rats jumped to the point of operation from a distance; some placed the fore paws on the end of the pla.ne a,nd pressed down; and still others i-an slowly around to the plane, halting an instant on the point of operation, and then continued the run ciround to the door. As in the maze, many of the inbred rats were sub- ject to errors vvnich persisted throughout the experiment. The results of the experiments for the inbi'ed rats fire iiiven in tables IXa, IXb , and IXc ; for the normal control series in tables Xa, Xb , and Xc. These t&bles ^ive only the averages of the three daily trials of individual rats. The shortest period of learning for an inbred, rat was tv/elve days; for a normal control, nine days. Fleven inbred rats and one normal failed to learn the incl ined plane problem within one hundred days. As in the maze tables, ,'ifter recordin^i the three perfect days of any one rat, the average of theitime for those three days was recorded on each succeeding dny in red ink. It is necessary to ijreserve these figures in oriier to compute the total daily averages based upon v/hich the curves of leai-n- in£_ are constructed. The particular value of tables IX nnd X is that they tiive the data in deta,i3 fron which the tables of comparative summaries are constructed. In table XI is presented a comparative summary con- eistinti of the daily avera(j,es of all the inbred and aD 1 the control rats used in the inclined plane experiment. From this table are constructed the comparative curves of learnint^. The table shows that eleven of the inbred and two of the normal rpts failed to learn the inclined plane. The inbreds required, on the average, "7?. 70+ daj/-8 to learn; the normals but 45.97-f. The absolute retention of the inbreds was, on the averai:,e, 31.842 seconds; of the normals, 22.587 seconds. All the inbreds had relearned at the end of the tv/enty-f ourth day; but all the normals had relearned at the end of the seventeenth day. The inbreds required, on the averae;e 6.74 days to relearn; the normals but 4.68, In all these criteria of ability the rats of the normal control series are shown, on the avera.^e, to be supei-- ior to those of the inbred series. The body length of the inbred rats \ised in the in- clined plane is, on the averaj^e a trifle ^-reater than that of the normals; the body weight is slightly less. The avera^je 'ictual brain wei^jht of the inbreds is less than that of the normals. The relative brain weitjht (in reference to body length) of the inbreds is 5.89;' less than that of the normals. The relative brain weight (in reference to body weitrht ) of the inbreds is 2 . ."^Bf^ less than that of the normals, i^lthout^li the inbred rats were killed, on the averat^e, at a more advanced age than the normal control, the percentat.e of water in brain 1^.6 ni)Q cord i.s ui^;nel•. The tpbles of cornparHtive Buraaarieo of inclined plane results support the hypothesip that the cieteriorution of Dr.-iin weight in a strain of rats is accompHnif^fl by deterioration in the ability to form hyt)it?. In Plate VIII is sliown the curve of learnint;; (belov/) and of relearninti (above) of the inbred rats conpared v/ith those of the normal control. The inbred curve is shown by the solid line, that of the control oy the broken line. The ordi- nates ^.ive the averaj^e time in seconds, and the abscissae the number of the day in which such time was made. As in the other learnin(_ curves, the average time for the first four days is given in fit:ures. The descent for the fii-at ten days is quite rapid, with one or two lapses. From the forty-first day the normal curve lies entirely below the fo\ir second mark. The inbred curve, throut^hout, shows great irregularities, especial- ly on the thirtieth day when it rises to an averat^e of near- ly twenty-eight seconds. The inbred curve of relearnint is very similar to that of the normal, and from the twenty- third day coincides with it. But it must be remembered that only the best of the inbreds were used in the relearnin^i experiment; eleven had failed to learn as at;^ain8t only two of the normals. The inbreds used had all rpl earned at tne end of the twenty- fourth day ; the normals at the end of the seventeenth day. In Plate IX may be seen the distribution curves of learning of both the inbred and control series for the inclin- ed plane experiment. The time is ^i^en in days — in tiroups of five for learnin^i, eint^ly for relearnin^i. As is the case with the mar.e experiment, it is very apparent that the advan- tate lies wholly in favor of the normal control series. Of the inbred rats used in the inclined plane expcri- I'rZ'f nent, fifteen were from the 7th t.ener».ti on, fourteen fron the 6th and one from the 9th. In Table XH 1h shown a conparative 8ununaj-y consistint;, of the daily averat'eB of all the 7th and all the 8th t^enerations (inclucint, with the 8th the one 9th {generation rat). The table shows that four of the 7th tjenera- tion and seven of the 8th tieneration failed to learn the in- clined plane. The 7th t^eneration required, on the avera^^e, 59.60 days to learn; the Bth (generation, 86.53 . The absolute retention of the 7th generation was, on the average 44.945 seconds; of the 8th generation, 13.8?5 seconds. All the 7th generation had relearned at the end of the twenty-fourth day; but all the eth generation had relearned by the end of the eighth day. The 7th generation required, en the average, 8 . no days to relearn; the Eth generation but 5.00 days. In these criteria of ability the 7th generation ex- celled in learning; the Sth in absolute retention and relearn- ing. But seven of the Sth generation as against but four of the 7th had failed to learn, and for that reason not tested for relearning. There eeerriS, on the v/hole but little differ- ence, but in the learning v/here all were used the advantage lies V7ith the 7th generation. The body length and body rveight of the 7th ^^enera- tion at^erage greater than those of the 6th. The average actual brain weight of the 7th generation is greater than that of the eth. The relative brain weight of the 7th generation (in reference to body length) is 5.20^j less than that of the 8th generation. The relative brain weight ( in reference to body weight) of the 7th generation is 13.93'' less than that of the 8th. The relative brain v/eights of the inbred rats used in the inclined plane has not deteriorated fron one generation to another, but has increased. The percentage of water in brain and cord of the 7th i^cnercJ.tion is t^renter than in the 8tVi. In Plate X ia shown tlie curve of learnin(£, (below) and of relearnlnt; (above) of the 7th and 8th (generations of inbred rats. The 7th tiSneration curve ia shown by the broken ]ine; that of the 8th generation by the solid line. The ordi- nates ^ive the tine in seconds, and the abscissae the number of the day in which such time v/as made. Both curvea in the learning aeries are very irregular, but more particularly that of the 8th tjeneration I'ats. Although irre^'ular, the 7th -^en- eration curve lies below that of the eth except in a few in- stances. After, the first day, the relearning curves are simi- lar and very re^nAlMr, although that of the 6th {generation re- mains below the 7th all the way. But only the best of the two generations were used, four of the 7th and seven of the 8th havinj^ been discarded on account of not having learned the inclined plane. 129 Rat ray 1 ray 2 Day 3 Day 4 Day b 7E56u' 15577.93 1205.60 139.93 50.60 30.00 7B57cr 814.7? 1978.93 207.93 108.67 61.27 7B58d' 1791.53 3299.80 80.60 36.27 16.33 7B69d' 7113.87 4745.00 591.27 336.20 44.00 7B70ci' 3413.33 2029.80 9 3.53 30.60 8.73 7B71d' 3901.20 403.60 14.07 14.07 17.07 7B72cr 2377.60 836.67 139.80 91.67 20.13 73734/ 5334.73 787.80 33.80 7.00 6.00 7Ae6cf 16621.33 57.00 16.40 32.27 4.13 7AS7cr 5442.67 94.40 68.27 9.13 6.73 7A8837 6.00 7.40 2.87 d.80 73570^ 7.93 3. SO 3.93 3.73 5.27 7B58d' ;:.09 2.09 2.09 2.09 2.09 7B69.J ij.yl 2.91 2.91 ;:.91 2.91 7B70d" 3.47 4.13 3.07 4.47 5.07 72 71 J- 5.20 5.33 5.60 2.47 4.00 7372d' 6.73 2.93 3.33 3.60 2.47 73730" 2.42 2.42 2.42 2.42 2.42 7A86cr 2.73 2.73 2.73 2.73 2.73 7A87d' 2.56 2.56 2.56 2.56 2.56 7A88d' 3.00 3.00 3.00 3.00 3.00 SBSej" 2.33 2.33 2.33 2.33 2.33 8S37c? 3.07 2.40 2.20 3.47 2.40 63390^ r.02 2.02 2.02 2.02 2.02 SElOcf 6.87 3.13 3.07 4.73 2.33 fiillJ 12.07 6.13 2.27 2.03 3.80 7359Q 8.20 5.47 3.73 6.13 2.53 7B609 6.47 6.73 2.40 3.87 4.80 7A91$ 2.78 2.78 2.78 2.78 2.78 7A3C9 2.87 2.87 2.87 2.87 2.87 8B40$ 3.40 8.27 3.00 3.27 3.93 8E16$ 3.93 1.80 2.87 6.53 2.60 8B179 2.24 2.24 2.24 2.24 2.24 SBie^ 5.80 5.07 6.47 7.93 4.33 8319c 4.67 3.80 4.67 5.00 4.00 33114$ 4.40 3.53 4.47 5.67 6.00 8B115Q 6.80 8.87 8.87 7.33 9.67 8B116$ 2.65 2.65 2.65 2.65 2.65 8A38Q 9B130$ 3.20 2.20 3.40 3.47 2.47 l.SO 5.67 2.47 3.33 4.40 Average 4.363 3.869 3.461 3.713 3.649 Table IXa. Inclined Plane Learning by Inbred Hats. 144 Rat if ray 76 Lay 77 Tay 76 Day 79 Lay 80 7L56g' 8.27 5.40 7.60 3.27 3.13 71570? 4.40 4.27 3.1? 2.60 3.07 7B58cf C.09 2.09 2.09 2.09 2.09 7369c" C.91 2.91 2.91 2.91 2.9] 7370d' 3.47 3.93 2.67 2.47 2.33 7B7}cf 3.37 3.20 3.13 3.40 2.93 7B72C? 5.60 3.33 5.93 3.20 4.47 7E73C? ?..42 2.42 2.42 2.42 2.42 7A86d' 2.73 2.73 2.73 2.73 2.73 7A87d' 2.56 2.56 2.56 2.56 2.56 7A88C? 3.00 3.00 3.00 3.00 3.00 8B36c^ 2.33 2.33 2.33 2.33 2.33 81337c; 3.33 4.87 3.40 3.47 2.80 83390" 2.02 2.02 2.02 2.02 2.02 SBlOo' 4.00 2.53 2.40 2.07 2.33 8B110- 3.80 4.67 4.13 2.80 3.07 7B59$ 4.73 8.40 5.33 29.67 14.33 7B60Q 5.20 4.13 12.80 4.60 2.73 7A91$ 2.7b 2.76 2.76 2.76 :..78 7A92$ 2.87 2.87 2.67 2.87 2.67 8B40$ ^.67 3.80 3.00 2.67 3.93 83160 3.73 3.00 3.13 4.00 2.60 631 7o 2.24 2.24 2.24 2.24 2.24 8B18Q 2.5? 3.67 4.93 4.07 10.53 8B190 831149 3.40 6.73 4.00 3.47 4.80 6.27 3.60 3.33 4.33 2.40 8311^9 5.73 8.33 4.80 6.00 5.27 83116$ 2.6';, 2.65 2.65 2.65 2.65 8A36Q 93130$ 5.07 2.13 2.00 3.00 3.'?3 5.60 3.'>26 3.47 3.07 5.60 4.40 Average 3.669 3.646 4.043 3.648 ?al3le IXa. Inclined Flar.e Learnint; by Inbred Rats. 145 Rat # Pay 61 lay Bil Day 8? Day 84 Lay 8! 7E56d' 713 5 7d' 7E5ed' 7B69c 7B70a- 7B71d' 7i72c" 7B73cf 7Ae6d' 7A87o' 7Ae8d" 8B36d" 8B:^7d" eLSgd" eBiod" 8Bllcf 7B595 7E60$ 7A910 7A92$ 8B40$ eE16$ 8217$ 88189 eB19o .14 eE114$ SBllbQ 8E116$ 8A38o 9B1309 3.87 2.67 3.40 3.00 6.00 5.87 4.13 6.13 4.27 2.47 U.09 2.09 2.09 2.09 2.09 2.91 2.91 2.91 2.91 2.91 2.49 2.49 2.49 2.49 2.49 4.47 3.13 4.33 5.40 3.53 2.60 1.93 3.67 -2.33 3.73 2.42 2.42 2.42 2.42 2.42 2.73 2.73 2.73 2.73 2.73 2.56 2.56 2.56 2.56 2.56 3.00 3.00 3.00 3.00 3.00 2.33 2.33 2.33 2.33 2.33 4.fi0 4.87 3.00 2.87 2.80 2.02 2.02 2.02 2.02 2.02 2.33 2.33 2.33 2.33 2.33 2.53 3.73 3.87 2.60 4.60 6.20 7.00 5.67 5.40 9.00 2.73 2.87 2.78 2.78 2.78 2.78 2.78 2.78 2.78 2.78 2.87 2.87 2.87 2.87 2.87 4.60 3.73 2.73 4.33 8.87 2.47 3.33 6.40 4.20 3.27 2.24 2.24 2.24 2.24 2.24 6.07 4.87 4.20 8.27 5.80 2.53 9.87 7.47 3.60 3.87 3.27 4.40 4.27 3.93 2.80 5.53 4.80 5.93 6.53 4.33 2.65 2.61' 2.65 2.65 2.65 2.73 1.80 4.07 2.07 2.20 5.07 5.40 3.40 2.67 2.67 Average 3.359 3.465 3.558 3.322 3.471 ;le IXa. Inclined Plane Learning by Inbred Rate. 146 Rat # Day 86 Day 87 Day 88 Day 69 Day 90 7E56d' 3.40 3.60 5. '^3 6.13 3.40 7B57d" 7.00 4.20 3.40 7.33 7.20 72580? 2.09 2 . 09 2.09 2.09 2.09 7B69cf 2.91 2.91 2.91 2.91 2.91 7B70cf 2.49 2.49 2.49 2.49 2.49 7B71cf 4.73 3.67 5.07 3.60 3.53 7B720" 2.60 3.53 2.80 '3.53 2.33 7E730' 2.42 2.42 2.42 2.42 2.42 7A86C' 2.73 2.73 2.73 2.7? 2.73 7A870"" 2.56 2.56 2.56 2.56 2.56 7A88d' 3.00 3.00 3.00 3.00 3.00 83360- 2.33 2.33 2.33 2.33 2.33 8B37d' 5.47 3.67 3.53 3.40 2.60 8B39cf 2.02 2.02 2.02 2.02 2.02 SB 1 Oct 2.33 2.33 2.33 2.33 2.33 SBlld' 7.27 3.33 8.00 7.73 10.13 7B590 4.40 3.93 3.5? 3.20 14.47 7B60$ 2.78 2.78 2.78 2.78 2.78 7A919 2.78 2.78 2.78 2.78 2.78 7A92$ 2.87 2.87 2.87 2.87 2.87 8B40$ 4.33 4.60 4.80 5.33 8.33 6B16Q 3.7? 3.00 7.7? 2.13 4.7? 8317$ 2.24 2.24 2.24 2.24 2.24 8E18$ 6.00 4.40 3.20 4.9? 3.60 8B19Q 8B114Q 6.93 10.53 6.07 2.67 2.60 3.73 2.33 2.60 3.80 2.60 8B116$ 6.60 6.27 7.80 9.9? 12.80 8B116Q 2.65 2.65 2.65 2.65 2.65 8A38Q 9B135$ 3.07 2.45 2.45 2.45 2.45 4.40 3.93 5.47 4.80 6.13 Average 3.729 3.388 3.686 3.639 4.170 Table IXa. Inclined Plane Leai-ning by Inbred Eats. 147 Rat # Day 91 Lay 92 Day 93 Day 94 Day 91^ 7B56cf 2.60 3.80 2.3? 3.53 2.80 7B57cf 4.7? 3.33 8.3? 2.47 2.40 7B58cf 2.09 2.09 2.09 2.09 2.09 7B69o^ 2.91 2.91 2.91 2.91 2.91 7B70c^ 2.49 2.49 2.49 2.49 2.49 7B71d" 7.80 4.5? 5.80 4.73 3.47 7E7i:u 2.60 3.60 4.00 ^3.80 2.87 7B73cf 2.42 2.42 2.42 2.42 2.42 7A66d' 2.73 2.73 2.73 2.73 2.7? 7Ae7d' 2.56 2.56 2.56 2.56 2.56 7A66d" 3.00 3.00 3.00 3.00 3.00 8B360' 2.33 2.33 2.33 2.33 2.3? eB37d^ 2.33 3.00 7.13 5.40 3.27 eE39d 2.02 2.02 2.02 2.02 2.02 8E10c? 2.33 2.33 2.33 2.33 2.33 8Bllc^ 7.00 2.80 3.53 5.60 2.80 7ii599 3.80 5.47 2.00 2.53 2.00 7L60q :j.78 2.78 2.78 2.78 2.78 7A915 2.78 2.78 2.78 2.78 2.78 7A929 2.87 2.87 2.67 2.87 2.87 8B40$ 4.60 5.67 6.67 5.13 3.33 8B160 2.47 5.87 8.60 3.00 3.07 8E175 2.24 2.24 2.24 2.24 2.24 8B18$ 4.80 4.67 9.00 5.93 18.73 eP19Q 8B114Q 6.33 4.40 5.67 3.00 3.53 4.80 4.07 4.20 2.7? 3.07 8B115Q 6.53 6.13 12.40 9.47 7.00 8BII69 2.65 2.65 2.65 2.65 2.6L^ 8A38Q 9B1359 2.45 2.45 2.45 2.45 £.45 4.00 3.80 3.40 5.9? 4.73 Average 3.501 3.393 4.124 3.463 3.457 'able IXa. Inclined Plane Learnint? by Inbred Rats. 148 Rat 7; I'ay 96 Day 97 lay 98 Day 99 Day 100 7B56tr 2.27 2.60 4.33 5.33 2.60 7B57CJ' 3.60 2.67 6.33 4.47 3.13 7B56d' 2.09 2.09 2.09 2.09 2.09 7B69cf 2.91 2.91 2.91 2.91 2.91 7B70d' 2.49 2.49 2.49 2.49 2.49 7B71cf 3.87 2.87 4.00 4.93 9.13 73720' 2.33 2. SO 2.30 -4.47 2.33 7B73o' 2.42 2.42 2.42 2.42 2.42 7A86d' 2.73 2.73 2.73 2.73 2.73 ixeid 2.56 2.56 2.56 2.56 2.56 lABSif 3.00 3.00 3.00 3.00 3.00 SBSed- 2.33 2.33 2.33 2.33 2.33 83370" 3.20 6.87 1.93 2.20 8.40 eE39cf 2.02 2.02 2.02 2.02 2.02 8B10C' 2.33 2.33 2.33 2.33 2.33 SBllcf 3.47 6.20 2.73 1.93 i.eo 7E59$ 2.16 2.16 2.16 2.18 2.18 7B60O 2.76 2.78 2.78 2.78 2.78 7A019 2.78 2.78 2.78 2.76 2.78 7A92$ 2.87 2.87 2.87 2.87 2.87 8B409 4.87 5.40 5.20 4.33 7.40 6B16Q 4.27 3.00 1.80 2.47 2.13 8B17$ 2.24 2.24 2.24 2.24 2.24 8Bieo 4.47 12.73 4.27 3.87 6.00 8B190 8B1145 2.27 1.87 6,07 2.53 5.60 2.47 2.76 2.76 2.76 2.76 8Blli3Q 7.13 7.87 17.20 5.07 6.73 6B1160 2.65 2.65 2.65 2.65 2.65 8A38Q 9B130$ 2.45 2.45 2.45 2.45 2.45 2.93 3.33 5,87 2.27 4.47 Average 2.999 3.460 3.604 2.982 3.510 ible IXa. Inclined Plane Learning by Inbred Rats. 149 Rat # i-'ailed to learn. Days required to learn. 7E56cf 7L57o 7B58d" 73690^ 7B70d' 7S71o' 7B72C? 7E73C?' 7A86cr 7A87cr 7AeSd' 8B36d" 8B37cf eB39cf 8B1 Od- es 11 o' 7B59$ 7B6n^ 7A919 7A929 8B409 SEieo 8B17$ 8B18$ eE19o eB114$ 8B115$ 8B116$ 8A38o 9B136$ 100+ lOOt 20 12 80 100+ 100+ 55 28 16 42 53 100+ 69 79 100+ 95 82 12 52 100+ 100 60 100+ 100+ 96 100+ 55 86 100+ Total Average 73.70+ Table IXa. Inclined Plane Learning by Inbred Rats. IbO First trial Rat # after 60 days' rent, 7E56d' 7B57C" 7B58cf 12.00 7B69d" ."56.20 7370^ 240.20 7P71<7 7B72cr 7B73cr 20.20 7A86d" 49.80 7Ae7ci" 52.20 7Ae8cr 2.80 8B36cr 31,20 8B37d' eB39J 17.40 8B10d' 25.60 8Blld' 7B59$ 18.00 7B60o 26.40 7A919 28.40 7A929 8.20 eE40$ eB169 6.00 8B17$ 6.20 8318$ eB19Q 8Bll4$ 10.60 8B115$ 8BII69 6.80 eA38Q 6.80 93130$ Average 31.842 Table IXb . Absolute Retention of Inbred, Hats, Inclined Plane. Ibl Rat ^f ray 1 Day C Day 3 Day 4 Day 5 7B56cf 7E57d' 7E58cr 7B69o^ 75700^ 7B71c; 7E72d" 7B73cf 7A86d' 7A87d^ 7A88d' 83360^ eB37cf eB39c' 8B10cf SBllc" 7B509 8B6C$ 7A91$ 7A92$ 8340$ 8216$ eB179 8B18$ 82190 eE1145 SBIISq eB116$ 6A38o 9B130$ Average 41.^/89 7.301 5.436 4.783 5.067 Table IXc. Inclined Plane Relearning by Inbred Rats. 9.67 6.93 5.73 10.60 11.07 88.07 33.20 11.07 9.87 24.13 209.87 8.40 2.47 2.47 2.47 73.13 6.73 16.20 16.00 5.53 266.33 7.13 3.00 3.00 3.00 27.13 11.27 5.20 4.67 5.67 2.47 ;..4 7 2.47 2.47 2.47 13.73 12.67 4.03 2.80 5.07 7.47 2.60 ::.60 2.60 2.60 11.53 3.87 6.47 6.53 6.73 8.13 4 20 11.07 2.53 2.53 20.20 9.13 3.40 2.73 2.73 15.87 7.93 5.40 4.80 5.80 8.67 4.53 3.53 4.20 3.67 4.93 3.33 1.93 1.93 1.93 7.53 3.47 5.00 4.67 3.20 10.07 5.71 6.47 3.07 3.07 4.53 2.87 4.07 3.67 2.33 4.67 2.27 ^.21 2.27 ::.27 Ib2 Rat # ray 6 Day 7 Day 8 ]jay 9 Day 10 7^560" 7E57cf 7E58u' 72 6 90^ 7P70u 7B71C? 7L7i:o' 7D73d" 7Ae6c" 7A87d' 7A88d' 8S36t.' 8B37tr 8B39cr SBlOd" SBllcT 7B59$ 7B6O9 7A91$ 7A92$ 8B40$ 8516$ 8B17$ 8B18$ 8r.l9o 33114$ eB115$ 8BII69 8A38Q 92130$ Average 5.175 4.239 3.404 3.186 2.828 ible I>;c. Inclined Plane Relearning by Inbred Rats. 2.07 2.07 2.07 2.07 2.07 24.87 12.40 11.47 9.27 2.80 2.47 2.47 2.47 2.47 2.47 10.93 6.27 4.13 3.07 3.60 3.00 3.00 3.00 3.00 3.00 7.40 6.53 6.47 5.33 6.60 2.47 2.47 2.47 2.47 2.47 7.13 5.47 2.73 2.73 2.73 2.60 2.60 2.60 2.60 2.60 5.53 8.80 2.60 2.60 2.60 2.53 2.53 2.53 2.53 2.53 2.73 2.73 2.73 2.73 2.73 6.33 2.60 ;..60 2.60 2.60 4.47 6.07 5.20 5.47 3.33 1.93 1.93 1.93 1.93 1.93 4.20 4.93 2.00 2.00 2.00 3.07 3.07 3.07 3.07 3.07 2.33 2.33 2.33 2.33 2.33 2.27 2.27 2.27 2.27 2.27 103 Pat ff ray 11 Day i:: Day 13 Day 14 Day 15 7E56C? 7B57cr 7E58cf 7B69d' 7B70cf 7B71cf 7B72cf 7i;7 3cr 7AS60" 7A87cf 7A88c" eB36d' 8337cf 83390^ 8B10c^ SBlld* 7li599 7B6C$ 7A91$ 7A929 8E40$ 8316$ 8B17$ 8B18$ 8219$ 85114$ 8B115$ 85116$ 8A38$ 9B13n$ Average 3.508 2.712 2.796 2.845 2.807 ?able IXc . Inclined Plane Learning, by Inbred Hats. ::.07 2.07 2.07 2.07 2.07 2.80 2.80 2.80 2.80 2.80 2.47 2.47 2.47 2.47 2.47 2.93 ::.93 2.93 2.93 2.93 3.00 3.00 3.00 3.00 3.00 3.93 4.27 4.93 4.93 7.47 2.47 2.47 ;^.47 2.47 2.47 2.73 2.73 2.73 2.73 2.73 ::.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.53 2.53 2.53 2.53 2.53 2.73 2.73 2.73 2.73 2.73 2.60 2.60 2.60 2.60 2.60 19.60 4.13 5.07 6.00 2.73 1.93 1.93 1.93 1.93 1.93 2.00 2.00 2.00 2.00 2.00 .).07 3.07 3.07 3.07 3.07 2.33 2.33 2.33 2.33 2.33 2.27 2.27 2.27 2.27 2.27 Rat # Lay 16 Day 17 Day 16 Day 19 Day 20 7E56a' 7E57d' 72580^ 7S69u 7S70.00 3.00 3.00 3.00 3.73 3.60 3.47 6.07 5.00 2.47 2.47 2.47 2.47 2.47 2.73 2.73 2.73 2.73 2.73 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.60 2.53 2.53 2.53 2.53 2.53 ::.73 2. 73 2.73 2.73 2.73 2.60 2.60 2.60 2.60 2.60 2.73 2.73 2.73 2.73 2.73 1.93 1.93 1.93 1.93 1.93 2.00 2.00 2.00 2.00 2.00 3.07 3.07 3.07 3.07 3.07 2.33 2.33 2.33 2.33 2.33 2.27 2.27 2.27 2.27 2.27 Rat f- Day 21 Day 22 Day 23 Day 24 Day 25 to 50 7B56d' 7r57u 7B5So' :J.07 2.07 2.07 2.07 2.07 7E69d' 2.80 2.80 2.80 2.80 2.80 7370^^ 2.47 2.47 2.47 2.47 2.47 7E71cr 7B72cf 7S73d- l;.93 2.93 2.93 2.93 2.93 7A660' 0.00 3.00 3.00 3.00 3.00 7A87cf 3.67 6.00 3.47 2.67 2.67 7A88cf -.47 2.4 7 2.47 2.47 2.47 6B36cr ;-.73 2.73 2.73 2.73 2.73 8B37cr SB39d' 2.60 2.60 2.60 2.60 2.60 SBlOcT 2.60 2.60 2.60 2.60 2.60 SBlld' 7B59$ 2.53 2.53 2.53 2.53 2.53 7B6O9 2.73 2.73 2.73 2.73 2.73 7A91Q 2.60 2.60 2.60 2.60 2.60 7A92$ 2.73 2.73 2.73 2.73 2.73 eB4 0Q ____- SB16$ 1.93 1.93 1.93 1.93 1.93 8E170 2.00 2.00 2.00 2.00 2.00 8B18$ S319Q SBlllj 3.07 3.07 3.07 3.07 3.07 8B1150 SSII69 2.33 2.33 2.33 2.33 2.33 8A38$ 2.27 2.27 2.27 2.27 2.27 9B130$ Average 2.607 2. 729 2.596 2.554 2.554 Table IXc. Inclined Plane Relearning by Inbred Rats. Ib6 Rat ,'i Failed to relc.irn. Dayo required to relearn 7B57d' 7^5Sv/ 7i6yu" 7370cf 1^71J 7S72cr 7373cf 7Ae6d' 7A87d" 7Ae8d' SBSecT PElOd' 8B11J 73599 73509 7A915 7A92$ 8340$ 8516$ 8317$ 8318$ 8319$ 83114$ 83115$ 83116$ 8A38Q 93136$ 6 10 3 11 3 24 1 8 2 8 4 4 7 15 Total Average 6.74 Table IXc . Inclined Plane Relearning by- Inbred Rata. 157 Body Body Brain Cord Water lentjth weight weight weight in brain Rat # in nm. in grma. in grms. in fc;rni«. y^ 7S56cf 219. 244.8 1.7819 .5906 78.^02 73571/ 207. 226.1 1.7418 .5807 78.21 7E58cr 205. 218.1 1.7199 .5295 78.44 7369cr 215. 243 .3 1.8771 .5908 78.84 7?,70d" 197. 184.0 1.7379 .5179 78.33 7^71^" 212. 240.6 1.8172 .5619 78.63 7372o^ 208. 237,7 1.8135 .5530 78.64 7373cr 206. 230.0 1.7880 .5770 78. 6y 7AS6cr 215. 221.6 1.7583 .5473 78.47 7A67CJ' 212. 247.2 1.7497 .5370 78.54 7A88o' 195. 168.8 1.5868 .5211 78.35 8B36cf 204. 205.7 1.7666 .5753 78.02 83370' 209. 232.4 1.9020 .5951 78.42 8339^" 190. 186.0 1.7305 . 5324 78.38 831 Ocf 206. 229 . 3 1.8112 .5813 77.74 831 IJ 195. 188.0 1.8329 .5468 78,36 7353Q 139. 148.6 1.6760 .5331 78.54 7360$ 190. 163.7 1.6802 ,5372 78.43 7A91$ 181. 99.4* 1.6030 .5317 79.00 7A929 181. 149.3 1,5989 ,4823 78.50 8340O 180. 140.2 1 . 67'' 0 .5059 78.62 8315$ 196. 175.2 1.7477 .5771 77.80 8317$ 191. 150.3 1 . 7009 .5556 77.95 3E1S$ 184. 160.3 l!7144 .5002 78.18 83190 83114$ 182. 147.9 1.6720 .4850 78.33 185. T ir» n 1.5945 .4793 78.07 83115$ 182. i3o!5 1.6040 .4914 78,11 83116$ 173. 122.7 1.5606 ,4924 77,83 eA3a$ 93130$ 189. 151.5 1.7154 .5363 78.70 180. 152.2 1.6711 .4910 78.26 Average 195.93 134.37 1.72083 .53787 78.363 Table IXd. AnatoiniG ial Data of Inbred Rate ) . *The extreraely light weight of this rat ic accounted for by the fact that she was in the last: stages of pneumonia when killed. Ibb Rat # V/ater in cord }0 Brain \vt . in relation to body lent^th. fj Brain wt. in relation to body weight. Atje killed. Days. VESecf 71.32 .81365 .72790 234, 7B57d' 71.10 .84145 .77037 234, 7B58d* 70.77 .83898 .78858 165, 7B69d" 72.05 .87307 .77791 297, 7B70c; 71.37 .38218 .94451 231. 7B71J' 70.97 .35717 .75528 231. 73720' 71.10 .37188 .76294 231, 7B73d' 72.01 .86796 .77739 231, 7A86cf 71.79 .81781 .79346 206. 7Ae7d" 71.94 .82533 .70781 206. 7A88G' 71.00 .81374 .94005 206. S336C? 71.30 .36598 .35882 206. 3B37d' 71.45 .91024 .81842 203, 38390" 72.24 .91079 .93038 206. 3310o' 70.36 .37922 .78988 239, SBllcT 71.12 .93995 .97495 191. 7B599 70.98 .88677 1.12786 234. 7S6O9 71.63 .88432 1.02639 231, 7A91$ 73.89 ,88564 1.61268* 206. 7A92$ 71.62 .88337 1.07093 206. 8B40$ 73.00 .92833 1.19187 200. 8B16$ 70.27 .89168 .99755 291. 8E17$ 71.38 .59052 1.13167 239. 8B18$ 71.21 .93174 3,06949 191. 8B190 71.38 .91868 1.13049 191. 8B114$ 70.54 .36190 1.15795 241. SEII59 71.37 .88132 1.22913 139. 8BII69 70.57 .90208 1.27138 241. SA380 71,68 .90762 1.13228 236. 9EI369 71.69 .92833 1.09796 192. Average 71.437 .37972 .97889 220. Table IXd . Anatomical Data of Inbred Rata. *The exceptional relative brain weight is due to the fact that when killed, this rat was in the last stages of pneumonia. \o9 Rat # Day 1 Day 2 Day 3 Day 4 Day 5 s H)77d' H)80c/ 981 . ..' 7 135.33 95.67 97.27 17.73 SI 747.13 359.27 144.53 30.60 11.73 s !I\7)lI4c? 830.93 4760.80 107.73 7.20 12.93 SI CW)l26d' 3426.13 310.07 49.80 15.93 20.20 SI HW 130d" 2484.07 1854.00 149.80 65.67 38.20 SI mv 131cf 2724.53 1022.73 145.33 25.13 7.27 SI [HV,' 132cf 3801.80 ]020.00 54.73 ' 7.60 6.33 S! ;HV,' 133o' [Iivr 134o' ;CH 140d" 3530.47 913.07 71.87 29. 67 5.40 S 1 2581.33 201.20 15.07 16!o7 7.13 s( 5504.13 562,40 487,13 82.53 30.13 SI V//HC)l43dC218.73 138.93 13.00 22.47 22.00 s( iCW 14 70^ 1922.47 375.73 64.87 11.80 57.47 s( ;C\V 1480' 3032,40 191.73 50.07 8.20 3.27 S( CW 14 9 J 958.80 752.80 73.93 109.13 7.60 s( ;CII 155-J" 4387.33 912.00 52.87 20.87 15.13 s( :CH)l56d- 1620.33 96.33 12.87 50.27 9.07 s C/EIi 73$ 3043.13 1916.33 132.87 39.47 9.13 s C/EB 74o 3573.40 1017.53 279.67 57.80 11.27 s ,H)8l0 ,CY/;i5s$ 220,07 637.33 586.73 152.80 18.73 s 196.73 1381.27 252.60 120.93 127.00 s( ;cy;)1292 2096.80 1347.80 287.40 549.40 129.47 s( CH 14lQ C:iil42o V//HC)T44( V//HC)l45' 2482.27 299.87 42.87 14.20 8.67 s 3296.67 256.07 24.60 12.27 20.73 s ?2775.33 576.53 237.07 102.67 28.53 s 23789.60 373.60 208.47 38.13 11.00 s( V;/rIC)l462l431.80 298.93 24.60 4.87 11.07 s( :-H)i575 : L1791.33 8596.67 64.13 12.20 6.80 s CH 159$ CH 150$ 2250.80 218.40 71.93 49.73 36.80 s 656.47 973.80 175.47 69.53 10.67 s( W/HC)166$4742.13 129.13 20.73 23.60 15.40 Average 2769.953 1072.722 133.287 61.600 23.995 Table Xa. Inclined Plane Learning by ilormal Rat?. 160 Rat ^ Day 6 Day 7 Day 8 Day 9 Day 10 SI (H)77cr (k)80cJ 33.47 23.40 31.67 14.07 S.87 £1 26.20 5.20 12.93 8.87 6.53 £1 [H\V 1140" 17.80 13.47 6.33 12.13 10.60 £1 CV; 126u 11.07 13.73 S.80 3.47 3.20 o 1 :iv/ i30d' 13.87 7.27 9.67 7.13 9.40 si Hvnisid" 6.40 14.07 3.53 10.40 4.13 SI ;iIV/ 132cf 2.87 4.20 4.73 3.33 2.07 SI ;H\V 133o^ 10.60 13.20 3.93 11.33 3.13 s( ;:i7; i34d' 4.00 2.73 2.67 2.73 ::.7i s( :CH)l40d' 7.93 8.80 11.93 10.07 3.93 s( :w/HC)l43c? 125.20 6.33 3.27 3.47 2.80 s( ;C^V 14 7cf 43.07 2.87 3.00 3.60 6.33 s( ,CV/ 143c? 4.40 5.73 7.13 2.60 6.47 s( CW 149d' 28.87 5.60 14.67 4.47 4.60 s( , CII ISSd" 30.47 14.67 6.67 10.20 6.60 s( [ciDibed' 12.67 35.27 9.47 23.60 11.00 s( ;cAb)73q 20.33 13.20 4.67 4.27 7.53 s( :C/I]3)749 13.73 8.93 14.13 51.60 3.93 s( :H)eio ■cw)i58$ 12.80 27.20 9.00 26.40 10.87 s( 188.20 21.80 13.60 6.13 6.73 G( ;cv;)i29$ 10.93 26.53 20.53 9.07 6.53 s( CH 141$ 13.33 11.40 4.93 9.53 4.00 s CH 142o :'.V,Aic)ll45 11.80 4.53 14.40 8.73 8.40 s ( 18.93 5.67 3.13 3.33 6.07 s ;"Ac)ii5$ 27.93 12.80 59.67 14.80 5.40 s W/HC)146$ 11.47 8.47 8.80 11.20 3.67 s :h)157q CII 159$ CHjloOo V//HC)166$ 5.00 8.47 14.87 28.67 18.67 s 4 5. 87 62.20 27.93 19.93 20.80 s( 8.60 4.87 8.87 6.33 5.60 s( 3.40 11.73 6.20 6.93 8.27 Average 25.874 13.478 11.704 11.280 6.961 Table Xa,. Inclined Plane Learning by Normal Rats. Rr.t # Lay 11 Day 12 Day 13 Day 14 Day 15 S(H)77cr 5.47 5.53 13. B7 3.27 4.60 StHjeOd" 5.73 8.27 9.33 9.13 9.67 S(HT7)114J 5.67 1.93 8.07 6.53 12.27 C(CV;)l26o' 3.00 5.80 2.93 2.80 11.80 S :i\V 1306' 6.60 4.73 6.20 3.67 4.00 S(:-{W ISlcT 8.60 7.73 6.07 6.00 7.53 s{H\V)132d' 3.20 5.73 2.20 "2.73 3.53 s(:r,v 133J" 2.40 2.00 ::.5i 2.51 ::.5i G(HA7 134o' 2.71 ::.71 2.71 2.71 2.71 S CH)140d' 17.27 14.27 4.87 6.07 2.67 S '.V/MC)143q' 3.18 3.18 3.18 3.18 3.18 S CVni47cr 5.73 7.60 2.47 2.13 2.27 S(CYni43^" 7.20 4.47 3.73 5.40 3.80 S Cr<7 149cr 9.40 7.27 3.33 6.13 5.60 S CII 155d" 7.00 6.33 4.87 10.13 3.27 C(cil)l56cr 8.53 10.67 5.60 7.87 3.20 S(C/liu)73} 7.33 8.33 8.13 9.87 5.87 S(C/^)749 3.07 6.00 3.47 5.53 7.07 S H)81o 5,47 7.87 5.47 9.67 4.67 S(CV;)128$ 3.47 3.73 4.60 10.47 4.07 G CV/jl29y 5.80 10.80 7.33 6.07 7.13 C CH 141^ 2.13 2.07 5.93 3.07 5.13 s(ch)142q 4.00 11.27 6.87 11.60 11.00 CHJ142Q S(v//iIC)l44$ 6.27 9.20 4.13 9.00 8.13 S(W/HC)1459 7.00 6.00 20.13 2.13 6.87 S W/HC)146$ 5.47 5.33 7.00 3.07 7.20 S(CK)1575 16.67 9.87 14.67 10.07 10.07 S CH 1599 21.13 12.13 5.80 39.80 19.07 S CH)1602 4.07 6.60 8.00 8.60 2.93 S(W/HC)166$ 7.20 8.33 6.93 2.13 9.47 Average 6.759 6.858 6.347 7.045 6.383 Table Xa. Inclined Plane Learning "by ITorraal Rats. I6i Rat ,r' Cay 16 Day 17 Pay Ifi Day 19 Day 20 s :i 77 J li 80o' 3.13 4.60 5.80 10.20 7. 87 s 6.93 6.13 7.73 4.67 3.67 s m'nii4c" 6.00 6.93 11.07 4.93 6.67 o i CV; 126J 0.53 6.33 7.93 9.20 6.40 s :i\v i30o' 5.60 7.73 10.07 5.20 3.07 SI H\7 131cr 3.20 4.87 5.67 4.60 3.13 SI H\V 132c^ 3.60 4.53 6.07 4.33 2.27 SI H\7 l^So* ;:.bl 2.51 2.51 2.51 2.51 SI :-r;/ i34d" 2.71 2.71 2.71 2.71 2.71 SI [?.--: 140c? 2.73 2.73 2.71 2.71 2.71 SI :^yAIc)l43d' rni5 3.18 3.18 3.18 3.18 SI ;CV/ 14 7cf 2.29 2.29 2.29 2.29 2.29 S( CW 1480? 7.67 6.07 12.00 9.53 14.27 SI ;C\7)l49cf 3.07 3.33 4.73 6.67 3.80 SI 6.87 8. 07 5.07 4.53 3.40 s( [CHilSocf 5.47 4!87 2.73 3.20 2.80 3( ;C/EB)73o 6.67 3.93 5.47 4.60 4.87 si :^ 4.93 SI Hiaod- 5.80 10.80 p I HV/ 114d' 2.13 1.89 Gl C\7 1260- 1.91 1.91 3 1 llfvV 13 Go 2.40 2.93 SI [m: i3io' 2.36 2.36 SI l}RVil32a 2.87 2.13 SI ;}r^ ISSc- 2.51 2.51 s( HW 134c' 2.71 2.71 s( 'CK 140d" 2.71 2.71 s( ;^;^/lIC)l4 3c 3.18 3.18 s( O^V 1470" 2.29 2.29 s( CV 1480' 3.27 2.27 s( ,CT/ 149cf 2.67 2.67 s( ;CK 155c" ;CH 156c" 2.49 2.49 s( 2.91 2.91 s( ;c/KB)73o 2.29 2.29 s( C/^'E)74q 3.02 3.02 3( :k)819 2.56 2.56 s( C\V)1285 1.53 2.1? s( CV;)l29o 5.00 3.67 c CH)l41.j 2.20 2.20 CI[)142q 2.75 2.75 s( 2.73 4.07 c( \7A:c)i459 2.69 2.69 s 7f/HC)l469 3.93 5.53 CK)1579 2.96 2.96 c( Cn)l599 2.85 2.85 s( CH)160$ V,'/}{C)1669 5.47 3.73 s( 5.49 3.67 4.80 5.47 6.93 8.87 1.69 1.89 1.91 1.91 2.71 2.71 2.36 2.36 '3.20 3.07 2.51 2.51 2.71 2.71 2.71 2.71 3.18 3.18 2.29 2.29 1.73 1.91 2.67 2.67 2.49 2.49 2.91 2.91 2.29 2.29 3.02 3.02 2.56 2.56 1.98 1.98 3.20 11.00 2.20 2.20 2.75 2.75 5.07 4.00 2.69 2.69 3.47 17.87 2.96 2.96 2.65 2.85 3.60 4.07 2.07 1.87 170 Rat ray 56 Day 57 Lay 56 Day 59 Day 60 S(K)77C ? Hieoc? £?}?:' )ll4o* s cv; i::6cf s(H\V)l?Od' S(Pf\7 l;51o- S(H\V)l32c' s ir.v)i3So S(in7)l34G' 3^)1400^ SJY/A:c)l43d' S C7/)l47d' S(c\7)l48d" S(CW)l49c' S(CH 155c- S(CH)l5fid' S C/EB)73o s(c/f;b)74$ S H)8l9 S C\0l28$ SOT 129$ S CK 141$. S(CH)142o S(V0iC)l44$ S(V;/IIC 145$ S V//HC)146q s(CH)157$ G(CIi;i59$ S CH)160$ S(r,/!{C)166$ 4.8'^ 8.13 1.89 1.91 2.71 :: . 36 2.53 2 . 51 2.71 2.71 3.18 2.29 1.91 2.67 2.49 2.91 2.29 3.02 2.56 1.98 2.7? 2.20 2.75 2.33 2.69 7.40 2.96 2.85 4.47 2.00 4.27 6.53 1.89 1.91 2.71 2.36 2.47 2.51 2.71 2.71 3.18 2.29 1.93 2.67 2.49 2.91 2.29 3.02 2.56 1.98 6.47 2.20 2.75 5.27 2.69 16.00 2.96 2.85 3.20 2.00 3.87 5.53 1.89 1.91 2.71 2.36 2.13 2.51 2.71 2.71 3.18 2.29 1.91 2.67 2.49 2.91 2.29 3.02 2.56 1.98 9.60 2.20 2.75 3.47 2.69 5.47 2.96 2.85 3.80 2.00 3.53 2.53 8.27 17.33 3.69 1.89 1.91 1.91 2.71 2.71 2.36 2.36 2.38 2.38 2.51 2.51 2.71 2.71 2.71 2.71 3.18 3.18 2.29 2.29 1.91 1.91 2.67 2.67 2.49 2.49 2.91 2.91 2.29 2.29 3.02 3.02 2.56 2.56 1.9« 1.98 6.47 5.00 2.20 2.20 2.75 2.75 3.67 4.20 2.69 2.69 4.27 7.93 2.96 2.96 2,85 2.85 3.60 4.33 2.00 2.00 Average 3.000 3.392 3.047 2.991 3.375 Table Xa. Inclined Plane Learning by Normal hats. 171 Rat # Pay 61 Day 62 Pay 63 Tay 64 Day 65 £:(K)77cr 8.07 7.1? S K)80d- 5.60 9.?? S(mv)ll4tf 1.89 1.89 S{CV/ 126c 1.91 1.91 S H\Y loOcf C.71 2.71 S HV.' 131cf 2.^6 2.26 S H\Y 1326' 2.38 2.38 S ir.V 133d" 2.bl 2.51 S H^.V 134c' 2.71 2.71 S CK)140J' 2.71 2.71 S(v,'/Iic)l4 3d' 3.18 3.18 S(cr,V)l47c" 2.29 2.29 S CW 148c? 1.91 1.91 S CVni49d' 2.67 2.67 S CK 155c/ 2.49 2.49 S(CH)156c- 2.91 2.91 C(C/EL)739 2.29 2.29 S C/PS)749 3.02 3.02 S n)eiQ 2.56 2.56 S(C"33 8.099 4.195 0.355 4.526 9.3SB ^ Ji»^ ±^ J^± X • V>\J«a^«.*-A C* V ^ • C .^M«.A...v>..A J W- .•»-. W*-U **w-.- Generation Inbred Ine? ^red Diane Results. 194 Learn ir.K ray 36 Day 37 Day 38 Day 39 Day 40 7th Avg. 8th Avg. 4.481 9.433 3.921 6.747 4.302 7.186 4.467 6.491 4.561 6.017 Learning Day 41 Day 42 Day 43 Day 44 Day 45 7th Avg. eth Avg. 4.667 5.13C 4.462 5.413 4.396 5.791 4.338 5.187 3.734 5.373 Learnine Day 46 Day 47 Day 48 Day 49 Day 50 7th Avg. Sth Avg. 3.435 4.587 4.121 6.031 3.636 4.027 3.867 6.116 4.277 5.933 Learning Day 51 Day 52 Day 53 Day 54 Day 55 7th Avg. eth Avg. 4 . 289 5.235 3.591 5.226 4.219 5.168 4.969 5.044 3.627 4.755 Learning Day 56 Day 57 Day 58 Day 59 Day 60 7th Avg. eth Avg. 3.251 4.893 3.584 4.247 4.406 7.412 7.917 4.553 4.325 5.581 Learning Day 61 Day 62 Day 6 3 Day 64 Doy 65 7th Avg. 8th Avg. 4.295 4.049 5.753 4.299 4.731 4.]43 3.006 5.627 3.331 4.151 Leaxnins Da.y 66 Day 67 Day 68 Day 69 Day 70 7th Avg. 8th Avg. 3.331 4.988 3.571 4.339 4.317 7.398 5.175 4.437 4.565 3.954 Table XII. Comparative Sumriary of 7th ond eth Generation Inbred Inclined Diane Eesulta. 195 I,earnin,.L ray 71 Day 72 Day 73 Day 74 Day 75 7th AVe;. 8th Avg. 4.415 4,350 3.717 4.021 3.388 3.533 3.233 4.3 93 3 620 3.678 Learning]! Day 76 Day 77 Day 78 Day 79 Day 80 7th Avg. 6th Avg. 3.760 3.691 3.601 3.736 4.130 3.162 4.705 3.361 3.623 3.673 Learning?. Day 81 Day 82 Day S3 Day 84 Day S5 7th Avg. 8th Avg. 3.319 3.398 3.039 3.891 3.322 3.794 3.135 3.509 3.424 3.519 Learning; Day 86 Day 87 Day 88 Day 89 Day 90 7th Avg. 8th Avg. 3.251 4.207 3.037 3.739 3.144 4.228 3.361 3.916 3.837 4.503 Learning Day 91 Day 92 Day 93 Day 94 Day 95 7th Avg. Sth Avg. 3.211 3.792 3.]57 3.629 3.273 4.975 2.91? 4.014 2.678 4.237 Learn in^' Day 96 Day 97 Day 98 Day 99 Day 100 7th Avg. 8th Avg. 2. '725 3.273 2.650 4.270 3.085 4.123 3.201 2.763 3.067 3.954 Failed to learn. Days to required learn. Absolute retention. 7th Avg. 8th Avg. 4 7 59.60+ 86. 53+ 44.945 13.825 Te.ble XII. Comparative Sununary of 7th and eth Generation Inbred Inclined Plane BesultB. 196 Relearnir^ Day 1 Day 2 Day 3 Day 4 Day 5 7th Avg. eth Avg. 66.322 8.058 9.265 4.438 6 . 322 4.218 5.756 3.443 f^..279 3.400 Relcrirnin,'; ray 6 Day 7 Day S Day 9 Day 10 7th Avg. eth Avg. 6.297 3.633 4.467 3.926 b.879 2.441 3.728 2.441 3.100 2.441 Relearning Day 11 Day 12 Day 13 Day 14 Day 15 7th Avg. 8th Avg. 4.285 C.441 2.909 2.441 3.055 2.441 3.139 2.441 3.073 2.441 Helearninp Day 16 Day 17 Day 18 Day 19 Day 20 7th Avg. 8th Avg. 2.733 2.441 2.721 2.441 2.709 2.441 2.945 2.441 2.848 2.441 Relearninp- Day 21 Day 22 Day 23 Day 24 Day 25 to 7th Avg. 8th Avg. 2.727 1..441 2.939 2.441 2.709 2.441 2.636 2.441 2.636 2.441 Table XII. Comparative Summary of 7th and 8th Generation Inbred Inclined Plane ResultB. 197 Failed to relcnrn. Days re qui to relccj red irn. 7th Avg. 8th Avg. 0 0 8.00 5.00 Anatomical Data Body length in cm. Body Brain weight weight in grns. in grns. (iord weight in grns. Water in brain 7th Avg. eth Avg. 202.13 169. '^'3 201.44 1.72S68 167.33 1.71299 .54607 .52967 78.542 78.185 .^iC.tcnical rata Water in cord '/o Srairt wt. :: in rclr+ion to in body length. b( Erain v;t. relation tc Ddy weight. Age ; killed. Days. 7th Avg. 8th Avg. 71.569 71.304 .85622 .90323 .90560 1.05218 223 217 Table XII. Comparative Summary of 7th and Sth Generation Inbred Inclined Plane Results. 198 :i.s.JI:B?,<:» ?% ri 199 li " ;i ' — ■ ci- ; p 200 - « « » ' f--iL-t..i-i-»_» t a-jL»-i t t. I f if '-;-i.i.;.i.t.!. 201 VI. SUmilARY Al^ID CONCLUSIONS. During the lont; course of experi:nentation, the re- nults of which are here set forth, the writer becffin? convinc- ed that the deterioration in brain weight ^nd in the ability to form habit9 were due, primarily, to the inbreeding. I v/ouTd not iiaint?iin that inbreeding, per se, is necessarily produc- tive of deleterious results if the parent stock be perfect in every respect; but it is iripossible, by eny neans at our comuand, to detei'inine physical perfection in any organism. As only t'vo strains of inbred rats v/ere used it seems best to ]et the question of the effects of inbreeding remain open until many strains of inbred rats, raised under different con- ditions of nourishment, teinperature, etc., have been subject- ed to parallel experiments. The two strains of rats used by me v/ere the products of inbreeding, and their brains were ab- solutely and relatively leas, on the averatje, in v/eight than those of the normal rata used as control. And, too, the abili- ty of the inbred rats to form habits agreed with the lesser brain weight in that they were inferior in both these respects to the normal control series. There vvere used in all the experi'ients one hundred and t'';enty-f our rats: sixty-two inbreds and aixty-tv;o normal controls. An equal number of males and females from inbreds and normals were used in each experiment. Table XI shows the distribution of relative brain weif^hts (with reference to body lent^th) of the inbred rats and of the normal control series. The inbred distribution is i-epresented by tlie lower curve, that of the normal by the upper curve. The tireatest frequency in the inbred curve occurs at .b6>: in the normal curve at .92>. The inbred d irtriL\i t ion ifi from .70;'; to .95*1; thftt of the novi'iMls from .84;.- to l.Ob^'. The average I'elative brain weit;ht (with reference to body lent^tli) of the f;ixty-two nor- nal rats if^ .9?3bl;.'; that of the inbredp is .fi73?b:.', or 6,44;' lens than that of the normal h. In order to comparp the ability of the rate of the leprer brain vei^it strtdri (inbred ratfi) vith a norna] control peries tiiree experimentB v/ere used: 1. The raz.e, in \vhich all the ratr, used vere riven five trials daily until they hed learned perfectly, or, fnilint, to learn, had worked one hundred days' (500 trials). At the expiration of sixty days after perfect learning the rats, except those failing to learn, v/ere tested for retention and relearnint^ until relearnin^ was perfect, or, failing: relearnin^;, for fif- ty days (250 trials). 2. The Preliminft.ry Inclined Plane, in vhich cill the ratp used were t.iven five trials daily for twenty days (lOO trials); at the expiration of sixty days after tliis period they were all tested for retention and relearnint ^or a period of five days (25 trials), 3. The Inclined Plane, in which all the rats used were .vi"^?" three trials daily until they had learned perfectly, or, fail- ing, to learn, h;^d v/orked one hundred days (300 trials). At the expiration of Hixty days after perfect learninji the rats, ex- cept those failin^; to learn, v/ere tested for retention and relearnint until relearnin,/ was perfect. In rill these experiments the str; in of ratr of lenr.er relative brain weight (the inbred?) learned less veil, on the averate, than the nornnl control scricE. In the r.tize and in- clined plane experimente the average number of days required to learn and relearn and the time of absolute retention wr« 203 far e,r«^uter in the cnse of the jnbi-ed rate than in thet of the nornal control Beriee. In the nuj.e experiment two inbrede and one norniil failed to ler.rn; tv/o inbrede faileo to relertrn. In the inclined plane experiment eleven inbreds and two aor- nal 8- failed to learn. The beyiavior of t};e normal rc-te confiiHting ptirtly of B strain, coupled v.ith tlie fact of their Desner relative brain vei^ht sujigestr. the importance of croHoint<, a strain of inbredp of lesser brain weight with nornal rats, and carry in^ out a series of tests such as have been presented in this pa- per, with two controls, one normal rats and one inferior brain weight inbreds. In the mase experiment the inbred rate of the 7th generation did a little less well than those of the 6th. In the inclined plane experiment the rate of the 8th generation, did a little less well than those of the 7th. It v/ould seem (althouvh rieteriojation of brain weight ce^ised after the 4th i,eneration of inbreds) that the ability to form habits deteri- orated progressively with successive generations. The writer had intended to attempt a correDation, if any exiPted, be-tween the number of days to learn a habit and the number required to relearn after oixty days. But al- most ell the rats relearned very quickly, v/ithoi... reference to the number of days required for learning; in nunbers, too, the rats were too few. An investit^tion along such :■ line should consist of but one relatively simple experiment; t\.o or three hundred rats of one sex only sliould be used; -mo the period of time between the completion of leurnini^ and the beginning of relearning should be lengthened to, ct the leant, ninety 6 ay a . The general result of the expeiimentn here o#t forth 204 may be sunned up hb fol.Towp: On the averj-it^e, the strain of inbred rate having an inferior bi-nin weight did lenu v/ell in Icarnin;^ to form habits than did the nornal control neriep. From these results tVie followine; may be fornulnted: Deteriora- tion in brain weight in a strain of rats is ucconpanied oy deterioration in the ability to form nabitB. 206 E 1 1 1 1 3 .- ». ^ - ■ tf : 8 1 I I . Ill ID s s sf : ?:d ^ 1 1 5j_" B " ■ 1111 ? ::_ izD s _L ^ T -^ 1 1 1 e I :P 1= i - p VITA. Gardner Cheney Basset was born in BoBton, I'nBBachu- cette, June 17, 3 873. Fe received hiH elen*ntj'ry -and Rerond- ary education in the public pclioola of BoRton and ilewton, I.'aHtui- chuBetts. From the year 1890 to the year ] 908 he wbs In the wholesale shoe business, Rerving successively as receivin4i clerlf, buyer, traveling' salesman and superintendent. He enter- ed the Collegiate Tepartnent of Clark University in 1908; wan assistant in Biology durin^i the year 1909-1910; asnistont in Psychology during the year 1910-1911; and in 1911 he receiv- ed the decree of Bachelor of Arts with highest honor. He spent the summer of 1910 at Cornell University in the Study of Ex- perimental Psychologj'. .In October, 1911, he entered the Johns Hopkins University, and was appointed University Fellow in that institution for the year 191^-1913. V/hile at the Johns Hopkins University, l.r. Basset studied Psychology under Drs. Watson and Dunlap, Psychiatry under Tr. Heyer, Genetics under Lr. Jennin(j.P, tmd Ueurologi' under Prs. Nail and Pgbin. ^