244 GREGOR T. POPA. 



tozoon turns in the fluid in such a manner as to show its larger 

 end, one can see very clearly even on fresh preparation, not 

 stained, the presence of this ring. It has different sizes, according 

 to the species (Arbacia and Nereis} and different outlines on 

 the same spermatozoon. Here and there it is thicker or thinner; 

 sometimes it becomes fragmented in granules and again, it forms 

 a compact mass. In Nereis (Fig. 5) there are normally two 

 swellings placed symmetrically, outgrowths of the ring, on which 

 one can distinguish two long filaments as in Fig. 5. In Arbacia 

 (Fig. 6), the ring shows in the same way various thickenings 

 (3-5) and these, not so constantly as in Nereis, support (usually 

 only one of them) a prolongation ended by a kind of knob. 



As the spermatozoon floats in the fluid, these filaments show 

 protean movements, elongation, shortening and thickening, very 

 similar to amoeboid movements. They are constructed of the 

 same material as the basal ring and they are to be considered 

 as prolongations of this. Provisionally they may be called 

 sensillx amoeboidex - 1 In all changes of osmotic pressure, in all 

 media which change or kill the spermatozoa, these sensillse 

 retract upon the ring where they produce granules projecting a 

 little above the general level. 



(b) Janus Green; Try pan Blue; Neutral Red 

 (i Per Cent, in Sea-water). 



These substances are frequently used for staining intra vitam. 

 The penetrating power is different for each. Janus green gave 



1 It is very interesting that the presence of these filaments was noticed by 

 Mischer "Die Spermatozoen einiger Wirbeltiere. Ein Beitrag zur Histochemie," 

 Verh. der naturf. Gesellsch. in Basel, 1878, Bd. VI.; the interpretation of them was 

 wrong. E. Ballowitz, in the same species, denies Mischer 's observations "Uber 

 die Samenkorper des Lachses. Ein weiteres Beitrag zur Kenntnis der Spermien 

 der Salmoniden," Arch./. Zelljorschung, 14 Bd., 1917, S. 451; but in an older paper 

 and in other species, " Untersuchungen iiber die Struktur der Spermatozoen, 

 zugleich ein Beitrag zur Lehre von feineren Ban der Kontraktilen Elemente. 

 Die Spermatozoen der Insekten," Zeitschr. f. wiss. Zool., 1890, Bd. 50, S. 317, 

 he himself has observed such filaments and even their movements. He even calls 

 them Wimpelfasern. The meaning of them is not explained, and he says that they 

 are "rdtselhajt." The conditions of observation were bad because he employed 

 always "maceration," after killing the spermatozoa. In fact, the sensillae are to 

 be observed much more clearly on fresh, slowly motile spermatozoa, without 

 stain. 



