ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 305 



and parts are almost normally proportioned in the permanently stunted 

 rats. Thus the early starvation apparently retards or inhibits the later 

 growth process of the body as a whole, with a few exceptions. J. A. T. 



Results of Early Removal of Thymus Glands in Tadpoles. — 

 Bennet M. Allen {Jonrn. Exper. ZooL, 1920, 30, 189-200, 1 fig.). 

 Experiments with Ranapipiens show^ed that the thymus glands from their 

 very inception exert no influence upon growth or upon the progress 

 of metamorphosis. They are not at any stage indispensable to life, 

 nor does their removal cause any marked deficiency in the general 

 metabolism of the body. Their extirpation does not affect the gonads, 

 nor the thyroid glands, nor any internal feature. J. A. T. 



Parathyroid Glands of Thyroidless Toad Larvae. — Bennet 

 Allen {Journ. Exper. ZooL, 1920, 30, 201-10). Removal of the 

 thyroid glands of Bi/fo causes a very marked hypertrophy of the para- 

 thyroid glands, so that they grow to many times the normal volume. 

 There is not in these parathyroids any deposition of colloid or evidence 

 of the assumption of a vicarious relationship. There are no noticeable 

 histological peculiarities in these hypertrophied parathyroids. J. A. T. 



Breeding of Dog-Perch. — Jacob PtEiGHARD (Report Michigan Acad. 

 Sci., 1913, 15, 10-1-5). In this fish the female is pursued by several 

 males, and after a tortuous course settles to the bottom. A male takes 

 position over her with his pelvic fins clasping her head and his tail at 

 the side of hers. Rapid vibration of the tail and fins (pectoral and 

 pelvic) of both sexes excavates a little pit in the sand. The eggs are 

 emitted, fertilized and buried. Each egg is weighted by a coating of 

 adhering sand-grains. Supernumerary males crowding round attempt to 

 supplant the pairing male. After spawning is finished at a pit the 

 female at least leaves the eggs. She repeats the process at many pits.* 

 The supernumerary males (and perhaps the pairing male) devour such 

 eggs as they can get. There is no parental care. There is colour 

 dimorphism between the sexes, but this is not the basis of discrimination. 

 If a male, substituted experimentally for a female, moves rapidly and 

 then stops on the bottom, it is treated by other males as a female. 



J. A. T. 



Factors in Variation. — Heber A. Longman (Proc. R. Soc. 

 Queensland, 1920, 32, 1-18). Against the view that evolution is an 

 unpacking of an original complex the author emphasizes the real 

 newness of the pouch of marsupials, the patagium of parachuting 

 mammals, the venom fangs of snakes, the pharyngeal teeth of fishes, 

 and the copulatory apparatus of the male dragon-fly. He suggests that 

 the evolution of environments w^ould provide stimuli which might have 

 cumulative effects in many generations. He lays emphasis on the 

 importance of environmental change in inducing mutations. The 

 general aim of the paper is to suggest a reconsideration of Lamarckism. 



J. A. T. 



The Method of Evolution.— E. W. MacBride (Scientia, 1920, 14, 

 23-33.) By the " force of heredity " is meant the tendency of the 



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