43'6 ^J. Karl Fiedler on the Development of the 



obtained by the two most recent observers, Ganin * and 

 Gcettef , however, do not agree in many points. 



Therefore, as my honoured master Prof. F. E. Schulze 

 recommended me to make a fresh investigation, I entered 

 npon it willingly, in the hope, if possible, of contributing 

 something to the clearing up of the affair. The chief part of 

 the work was executed during the summer term of the 

 present year in the Zoological Institute of the University of 

 Berlin, and I would in this place express my most sincere 

 thanks to Prof, Schulze for his assistance therein. As 

 material I had at my disposal Spongilla fluviatilis, which 

 abounds in the Spree. A detailed statement of my results I 

 hope to be able to publish shortly ; here I shall only briefly 

 indicate what relates to the formation of the ovum and semen. 



In the first place, in opposition to Gcette's notion I must 

 maintain the unicellularity of the ovum of Spongilla. Gcette's 

 own figures furnish no absolute proof of his view, according 

 to which from the primordial ovum there proceed several cells, 

 one of which grows to a large size, while of the others some 

 take part in the formation of the follicle, and the rest become 

 amalgamated again with the large cell. Thus '' only is the 

 foundation of the ovum completed." In the ovicell I have 

 always found distinct cell-limits, and, what appears to be 

 conclusive, only a single nucleus, I lay the more stress upon 

 the latter circumstance, because I have succeeded, by double- 

 staining, in clearly distinguishing the nuclear and vitelline 

 formations. In single-stainings a confusion in this respect is 

 almost inevitable, and Goette may in this way have been led 

 astray. The method of double-staining with picro-carmine 

 and bleu de Lyon, introduced by Maurice and Schulgin| and 

 recently advocated by Blochmann§, gives, after a short 

 washing of the sections with a little ammoniacal alcohol, a 

 fine red coloration of the nuclei and a brilliant blue coloration 

 of even the smallest particles of the vitellus. 



Thus also it appeared that in the ovum the large round 

 vitelline globules do not, as Goette thinks, make their appear- 



* M. Ganiii, " Zur Entwicklung der Spongilla Jluviatilis" in Zool. 

 Anz. i. 1878, pp. 195-199, and ' Beitrage zur Keuntniss des Baues und 

 der Entwicklung der Schwamrne ' (in KuSvsian), Warsaw. 



t A. Goette, " Untersuchungen zur Entwicklungsgeschichte von Spon- 

 gilla fliidatilis" in 'Abhandl. zur Entwicklungsgeschichte der Thiere/ 

 Heft 3 (Hamburg and Leipzig, 1886). 



X Maurice and Schulgin, ''Embryog^nie de V Amour ouciutji proliferuni," 

 in Ann. Sci. Nat. Zool. s^r. 6, tome xvii. p. 6 (1884). 



§ F. Blochmann, " Ueber die Reifung der Eier bei Ameisen und 

 Wespen," Festschr. zur Feier des 500 jahr. Bestehens d. Ruperto-Oarola, 

 issued by the Naturh. Ver. zu Heidelberg, 1886, p. 118. 



