558 BULLETIN OF THE 



appe:n'dix. 



Of the numerous papers bearing on the. topics here considered which have 

 come to hand too late to be reviewed in their proper connection, I shall give 

 an account of only those of Fol, Mayzel, and Perez ; — those of the two last- 

 mentioned authors, because they are based upon the observation of animals 

 very nearly related to Limax campestris; that of the first, because present- 

 ing features of general interest, as well as many theoretical considerations 

 concerning matters which I have discussed. 



Mayzel's ('79) paper is a brief notice of the nuclear metamorphosis during 

 segmentation as observed in the case of nematodes and Limax variegatus. His 

 observations were first made public at a session of the Warsaw Medical Society, 

 Nov. 26, 1878.* 



The author undertook these observations primarily with the ol;)ject of ascer- 

 taining whether Auerbach's view of a karyolysis or Brandt's theory of an amoe- 

 hoid nuclear division best explained the phenomena. He therefore selected 

 for study Ascaris nigrovenosa and Strongylus auricularis. It is only as acces- 

 sory evidence that Limax is introduced, and there is no attempt made to pre- 

 sent a connected history of the early stages of its development. 



The best success was reached by the use of acetic acid, and of the nematodes 

 Strongylus proved to be the more favorable for study by this process. Mayzel 

 succeeded in demonstrating in the nematodes mentioned the existence of the 

 typical fibrous Kernspindel, with granular equatorial Kernplatte, and fibrous 

 rays around the poles of the spindle. The presence of a small spindle located 

 at the periphery warrants the inference that the elimination of a polar globule 

 is preceded by the formation of a maturation spindle. 



In Limax the author also found the spindle, nuclear plate, and astral figures, 

 which accompany the first cleavage. The spindle consisted of very numerous 

 closely packed, smooth filaments ; the nuclear plate was composed of highly 

 refractive granules of unequal size ; the astral figure, of fibres very similar to 

 those of the spindle. f I can corroborate for the species I have studied the de- 

 scription he has given, but insist upon the ultimate development of a more prom- 

 inent distinction between the spindle fibres and the stellar rays than he seems 

 to have observed. These differences in the condition of the spindle fibres may 



* See Mayzel '79«, '79^ and '79^ 



t "Ebenso sind die sonnenforinigen Figuren an den Polen der Kernspindel aus 

 aiisserst zahlreichen, glatten und somit den Spindelfasern ganz ahnlichen, gleichfalls 

 sicher wahrzunehmenden Faserchen zusammengesetzt, bestehen mithin nicht aus in 

 Reihen angeordneten Kornchen; letztere fiillen zwar die Zwischenraume zwischen den 

 Fasern aus, lassen sich aber durch Druck auf das Deckglaschea leicht herauspressen." 



