ZOOLOGY AND BOTANY, MICROSCOPY, ETC. ITO' 



Janus green. In the case of the sand-dollar {Echinorachnius parma) 

 slightly stained spermatozoa were in a few cases able to fertilize ova ; 

 slightly stained eggs were occasionally fertilized by stained or unstained 

 spermatozoa ; in most cases Janus green was fatal, but brilliant cresyl- 

 blue and neutral red proved true vital stains, for development went on, 

 though the cells showed stained granules. The ova of the angler 

 (Lophius piscatorius) developed into embryos in neutral-red solution, 

 and the cells showed stained granules. Many details are given in regard 

 to ova and spermatozoa and the influence of various stains. 



Inheritance of Fertility in Sheep.* — E. N.Wentworth finds evidence 

 that sheep of high birth-rank tend to produce offspring of high birth- 

 rank. Data referring to Southdowns indicate that the highest record 

 of a ewe is a better selection standard for high fertility than a random 

 record. The frequency of multiple births in sheep varies with the 

 breed. Inheritance is affected by the vigour of the ewe, the feeding and 

 age of the ewe, the season and region. There seems to be no relation 

 between high fertility and additional mammge. There is no evidence of 

 a sex linkage of fecundity factors in the pedigrees tabulated. Evidence 

 from Shropshire triplet pedigrees suggests that triplets are genetically 

 different from twins and singles, which two are probably genetically 

 alike. 



Development of Mammary Glands in Rat.f— J. A. Myers has 

 studied this in male and female albino rats from the late foetal stages to 

 ten weeks old. When the gonads are in the indiiferent embryonic stage, 

 there is no apparent difference in the primordia of the mammary glands 

 in the two sexes. At eighteen days the primordia in the male differ 

 from those of the female in possessing no mammary pit ; at twenty 

 days, when the nipple primordia are present in the female, they are 

 absent in the male ; the nipples fail to develop in the males ; the 

 epithelial hood is also absent. Until about the fifth post-natal week 

 the milk-ducts of the two sexes are much the same ; in the ninth week 

 (age of puberty) the ducts of the female branch very profusely, while 

 those of the male show little change. The second inguinal gland in the 

 male is rudimentary or absent. The number of glands is more variable 

 in the male than in the female. 



Effect of Stress and Strain on Bone Development.^ — J. A. 

 Howell followed Pottorf in observing the effect of cutting the main 

 nerves of the branchial plexus on the right side of puppies (about four 

 weeks old) in order to produce paralysis of the muscles. To the question 

 whether all bone-growth is dependent upon the amount of stress and 

 strain, the answer is definitely in the negative. Bones deprived of the 

 action upon them of all but a negligible amount of stress and strain 

 grow considerably. But the answer to the question whether bone- 

 growth is entirely independent of the action of stress and strain is also 

 definitely in the negative. This is shown conclusively by the very 



* Amer. Nat., li. (1917) pp. 662-82. 



t Anat. Record, xiii. (1917) pp. 205-26 (7 figs.). 



t Anat. Record, xiii. (1917) pp. 233-52 (1 figs.). 



