70 



Die Urniere, -welche bekanntlich eine innere ist, bildet sich 

 jederseits aus einem Haufen von Mesodermzellen, in denen bald eine 

 Höhlung entsteht. Die Säckchen Avachsen bald je zu eiuer Röhre 

 aus, deren eines Ende an die Oberfläche rückt, das Ectoderm durch- 

 bricht und somit eine Öffnung nach außen erhält. Das entgegenge- 

 setzte Ende der Röhre zeigt im Inneren eine Flimmerung. Eine innere 

 Mündung der Urniere ließ sich nicht mit Sicherheit nachweisen. 



3. On the Formation of Eggs in the Testis of Gebia major, De Haan. 



By Dr. C. Ishikawa, Imperial University, Tokyo, Japan. 



eingeg. 10. Januar 1891. 



The male generative organ of Gebia major is a paired tube lying 

 in the thorax and abdomen extending from the hind end of the dorsal 

 part of stomach to the first half of the telson, just above the point 

 ■where the anus opens. These tubes are united at both ends and thus 

 form a continuous ring, the united parts forming a short unpaired 

 tube. A glance at Fig. 1 will show clearly that they are not of equal 

 ■width throughout their length, but that the anterior half is much nar- 

 rower than the posterior. The vasa deferentia (v.d.) arise from the 

 first third of the anterior narrower part, and run as usual much convo- 

 luted down and backward to end on the basal segment of the last tho- 

 racic limb. 



In fresh specimens . the posterior wider portion appears of an 

 yellowish colour and has even to the naked eye an undoubted resem- 

 blance to the ovary, while the anterior narrower half has to all appea- 

 rance the form and structure of a testis. 



Beginning with the anterior part, the testis proper, the tube pre- 

 sents, along its entire length, a germinal band , in which young sper- 

 matic cells are to be found. These (spermatic cells) multiply as usual 

 by the karyokinetic division and produce spermatozoa, which lie in 

 the saccular swellings of the testicular tube. The [ripe spermatozoa 

 (Fig. 2 a) appear nearly of the same shape as that of Gebia littora- 

 le as given by Prof. Grobben in his beautiful researches on Decapod 

 spermatozoa. The only difference being, in our species, a spermato- 

 zoon is much smaller than those of the european species , and presents 

 a rectangler shape when seen from the side and not oval; the sides free 

 from spines being flattened. It has moreover a round refracting body 

 (centrosoma/ near one of the flattened surfaces on the side of the 

 nucleus. Treated with FI e mm ing's solution , the entire spermato- 

 zoon shows a narrow dark coloured peripheral protoplasmic) zone 



