30 THÉEL, HERMAPHRODISM IN HOLOTHURIDS. 



The destruction and absorption of egrgs and 



tissues. 



It was said before, tliat, in Mesothuria intestinalis, the 

 posterior portion of the genital basis devoid of genital tubes 

 successively increases in size. Tbis takes place at the cost 

 of the tubes situated immediately in front, which, by degrees, 

 become obliterated. This enlargement, however, is k^pt within 

 proper limits, because the free curved end of the basis gra- 

 dually diminishes by absorption and atrophy. Besides, it has 

 been noticed that some genital tubes often present a colour 

 different from that of the others. A careful microscopic in- 

 spection reveals that this is due to a process of destruction of 

 the egg-cells within the tubes, causing them to aquire a pecu- 

 liar colour easily distinguishable in fresh specimens. In both 

 cases, the wandering cells should play a predominant part in 

 the process of destruction. 



It lies far beyond the limits of this paper to pay any 

 attention to the great number of papers which treat of the 

 dissolution of tissues and organ-systems (histolys), and where 

 the question has been discussed as to what part the wander- 

 ing cells (leucocytes, phagocytes etc.) play in these processes 

 as well as in the destruction of minute foreign bodies.^ 

 Varying views have been propounded, but Metschnikoff's pha- 

 gocytosis is still sustained by many distinguished investiga- 

 tors. 



My own observations support the views of Metschnikoff. 

 the eggs in Mesothuria intestinalis being attacked and ingested 

 solely by amoeboid cells. Concerning the atrophy of the 

 posterior portion of the genital basis, a fatty degen eration 

 may take place, though even here the chief work of destruc- 

 tion is carried out by the phagocytes. It is a fact already 

 well known, that in several forms of Metozoa the eggs and 

 spermatozoa are destroyed by the phagocytes. In 1880, Schnei- 

 DER^ pointed out that amoeboid cells are met with within the 



' Comp. the works of Metschnikoff, Barfurth, Looss, Korotnepp, 

 Ebert, Noetzel etc. 



^ tjber die Auflösung der Eier und Spermatozoen in den Geschlechtsorga- 

 nen. — Zool. Anzeiger III, 1880, N:o 4t3. Thanks to PpLtGER, His, Lindgren, 

 Wagener etc. we have been made acquainted with the immigration of granu- 

 losa-ceUs within the mammalian ovum, bnt the respective interpretations of 

 this phenomenon vary. 



