and Laboratory Methods. 157 « 



while the unpigmented area at the vegetal pole gives rise to the primary mesen- 

 chym and larval skeleton. Boveri holds that the micropyle represents the point 

 of attachment of the ovocyte, and that the chief axis of the embryo is therefore 

 traceable back to the germinal epithelium of the ovary. s. j. h. 



Holmgren, N. Ueber den Bau der Hoden und The seminal tubules of the testis in 

 die Spermatogenese von Staphvlinus. Anat. „, , ,. ,.rr i • i-rr 



Anz. June looi. Staphyluius diner much m different 



seasons of the year. In summer the 

 outer zone of the tubules contains spermatocytes and spermatids, and the inner 

 zone is filled with spermatozoa. No spermatogonia are present. In animals 

 killed in the winter the capsules of tubules are thickened except over a portion on 

 one side where the tubule is swollen out. This swollen part contains, besides a 

 Verson's cell, only spermatogonia ; the latter differ from the spermatogonia of 

 the rest of the tubule in size and structure, and become arranged radially around 

 the Verson's cell. No spermatocytes of the second order, nor spermatids, are 

 found at this season, but there are a few spermatozoa which represent remnants 

 left over from the previous summer. The thick outer capsule of the testis is a 

 syncytial membrane from which the spermatogonia arise. The spermatogonia 

 become enclosed in packets, surrounded by a capsule derived from the main 

 capsule of the tubule. The spermatozoa that are not discharged are finally 

 ingested by the capsule and resorbed. This is apparently a normal process of 

 utilizing the unused spermatozoa. The spermatogonia of both parts of the 

 tubule, although they differ much in structure and history, give rise to sperma- 

 tozoa, which, so far as could be determined, are all alike. It is a fact of interest 

 that the same kind of specialized cell is developed by two different routes. 



S. J. H. 



Conklin, E. G. The Individuality of the Germ In Crepidula platia it is very probable 

 Nuclei during the Cleavage of the Egg of , , i • i , 1^1 



Crepidula. Biol. Bull. II, June, 1901. that the germ nuclei do not completely 



fuse, as is indicated by the double 

 character of the nuclei, which can be traced to quite an advanced period of 

 cleavage. The double nature of the nuclei appears most clearly during the 

 telophase of each division, but may sometimes be observed throughout the entire 

 resting period. The chromosomal vesicles, when the daughter nuclei are being 

 formed, fuse into two separate groups, which, for a time, are separated by a 

 partition wall. In the early cleavage stages two nucleoli are present. These 

 may represent the descendents of the nucleoli of the male and female pronuclei, 

 as each pronucleus possesses a nucleolus. It is probable that the half of the 

 nucleus lying nearest the animal pole of the egg is derived from the female 

 pronucleus, and the other half from the sperm. s. j. h. 



Petrunkewitsch A. Die Richtungskorper und ^he theory that the unfertilized eggs of 



ihr bchicksal im befruchteten und unbe- •' °° 



■ fruchteten Bienenei. Zoologische Jahr- bees give rise to drones is supported 



bucher, Abth. f. Anat., July, 1901. ^^ ^^e observations of the author, who 



finds that the eggs laid by the queen in the drone cells are always unfertilized. 

 In both the fertilized and unfertilized eggs the first maturation division is an 

 " equation division." The first polar body divides, the outer portion being 



