ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 15 



the most obvious phenomena of division, which he himself so care- 

 fully discriminates, have in all probability the least significance, has 

 the merit of promoting further inquiry. Equally poetic and scientific 

 is his conception, that the wonderfully striking series of shiftings 

 and transformations, displayed as in a panorama by the coloiu-ed 

 filaments, may be ascribed to the influence of pale, almost invisible 

 structures, whose presence, like that of presiding demons, is made 

 known by their works. 



The third Section is occupied by the more special topic of 

 spermatogenesis in Salamandra. He corroborates v. la Valette's 

 account of the production of spermatocytes from multinuclear sper- 

 matocysts, and adds descriptive details as to the indirect division of 

 the nucleus. The head of the spermatozoon lies at first within the 

 nuclear membrane ; it is not formed from the whole nucleus, but 

 from the chromatin only. Flemming is not certain as to the mode of 

 development of the middle segment. 



In his remarks on technical methods, Flemming cautions us 

 agaiust some sources of disappointment and error, especially as 

 touching the misuse of chromic and picric acids. He recommends 

 slow and careful staining with hjematoxylin, whenever the finest 

 results are needed. He chiefly employs such preparations, made in 

 great number ; in a few cases he has worked with living structures. 



Flemming continues to cite the principal contemporary writers on 

 cell-division, and gives a further list of others, both old and new, 

 whom he refers to in his Section on the development of spermatozoa. 

 He selects for more detailed comment those memoirs of Klein, 

 Peremeschko, Schleicher, and Strasburger, which he has seen sub- 

 sequent to the printing of his first Part. Klein's independent 

 researches very powerfully support most of Flemming's conclusions. 

 Notably is this the case as to the determination of the phases which 

 constitute the regressive series. These have been overlooked, if not 

 as merely existent, in regard to their true connection and derivation, 

 by all other observers, including the acute and painstaking Stras- 

 burger. On but one important physiological point do Klein and 

 Flemming differ. Klein believes in the occasional occurrence of 

 direct division among fixed cells. Flemming, otherwise interpreting 

 what Klein has seen (pp. 159-162), considers that such direct division 

 has in no case been hitherto demonstrated, though its possible display 

 by amoeboid cells cannot yet be categorically denied. Flemming 

 (p. 169) lays more stress than Klein on the equatorial plate as con- 

 stituting a definite phase. This phase Klein is inclined to ignore, 

 jumping rather too suddenly from the parent monaster to the re- 

 gressive stellate figure [but why should not precocious develop- 

 ment, i. e. abbreviation, here take place in some instances ?]. In 

 describing the monaster of Triton, Klein makes no mention of 

 longitudinal splitting. Peremeschko, however, has seen the 

 cleft filaments, without recognizing their full significance. Pere- 

 meschko, like Schleicher and Strasburger, errs in deriving some or 

 all of the nuclear filaments from grown granules. He makes other 

 mistakes (pp. 164-9), both of omission and commission, not rightly 



