ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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of endothelial cells, and may be sinusoids which persist from the primary 
sinusoidal circulation of the heart. The haemorrhages apparently occur 
by diapedesis from the vessels of Thebesius. No other pathological 
conditions were found in the affected valves. J. A. T. 
7- General. 
Parabiosis in Rats. — Naohide Yatsu (. Anat . Record , 1921, 21, 
*217-28, 7 figs.). Parabiosis is the term applied to a union of the 
•circulation of two animals ; heterosexual parabiosis means the circulatory 
union of a male and a female. The spermatozoa remain functional ; 
the prostate is not affected ; some Graafian follicles are normal, and 
corpora lutea are formed ; a large majority of the follicles undergo 
regressive changes ; the uterus is not markedly changed. When the 
male is castrated the ovary of the other shows no normal follicles, nor 
corpora lutea ; the uterus is affected. This is probably due to some 
influence of castration on the endocrine organs of the male. The testis 
is not affected at all by the union with either spayed or normal 
female. J. A. T. 
Catalase Content of Organisms. — J. H. Bodine (Jour) i. Exper. 
Zool., 1921, 34, 148-8, 3 figs.). In grasshopper, firefly, and potato- 
beetle the catalase content decreases with increasing age and body 
weight. The rate of C0 2 output and catalase content seems to vary in 
the same direction, but in “ hibernating ” forms a marked decrease in 
C0 2 output takes place with no corresponding change in catalase 
oontent. Starvation results in decreased amounts of catalase. Further 
quantitative data regarding catalase content and C0 2 output are 
required before any definite relationship between the two can be 
established. J. A. T. 
Analogies between Dice-casting and Breeding. — Harry M. 
Laughlin ( Genetics , 1921, 6, 384-98, 1 fig., 5 tables). The statistical 
analogy between dice-casting and certain breeding phenomena is in 
many respects very close. There are, of course, many differences between 
dice-casting and breeding phenomena, but they have this in common, 
in both dice-casting and organic reproduction the experimenter is 
permitted to see, at first, only a single value (the phenotype in life ; the 
upturned face if a die), in a given individual ; but if he continues the 
processes (dice-casting or breeding) long enough, he can test the range 
of variability possible to the “ offspring ” of the original “ parental ” 
individual. All of the essential phenomena of schemes of selection and 
the mathematical treatment of their counts may be clearly shown with 
the dice. The parallel is especially clear-cut if the analogy be to pure 
lines. The tables show schemes of recording variation, regression and 
correlation ; how selection processes, without creation, secure the highest 
values potential within a particular line ; how for breeding purposes a 
low value from a good strain is better than a high value from a poor 
strain ; how selection only sorts ; and so on. J. A. T. 
