Japanese Tricladida Maricola. 1 1 



tive nature, presenting no peculiar structure. 



Of interest is the complete absence of rhabdites in the previ- 

 ously recorded limulus-infesting Bdellourid-species, except one 

 form of Bd. pro'plngua, in which they are but rarely found. 

 However, they are in Ect. limuU very abundant on the dorsal 

 side. 



The formation of the rhabdites has long been a much debated 

 question. By a number of investigators it was alleged that they 

 originate only in cells, found scattered in the l^ody-parenchyma 

 directly inwards to the dermal musculature; while a few writers 

 [BöHMiG (5), Ude (55), Weiss (61)] assumed their formation to !>& 

 partly in the subcutaneous cells and partly in the epidermal cells. 

 Now I am apt to acknowledge the latter view. In the species 

 examined, the rhabdite-forming cells are scattered in the paren- 

 chyma inmiediately near, or farther inwards to, the epidermis, as 

 observed by some authors. The passage by which tlie rhabdites 

 reach the epidermis through the parenchyma and the basement 

 membrane could frequently be brought under observation. In 

 both Pr. lactea and Ect. limuli the subcutaneous cells are found 

 sparsely in the parenchyma, in spite of the abundant occurrence 

 of rhabdites in the epidermis. To my mind, the fact probably 

 stands in favour of the view that the formation of rhabdites takes 

 place partly in the epidermal cells. 



The question concerning the physiological meaning of rhab- 

 dites has also been long debated on by naturalists. Some writers 

 considered the rhabdites as homologous to the nematocysts of Coe- 

 lenterates, whereas more recent authors would ascribe them to the- 

 equivalents of gland secretions. I entirely concur with tlie latter 

 opinon. The rhabdites are given off freely on the dorsal as well 

 as on the ventral surface. When they are discharged a sticlcy 

 gelatinous fluid is poured out with them. If the worm be placed 

 in a dish with a ver}' little water, or irritated in any way, a rapid 

 discharge takes place, and the worm becomes enclosed in a 

 whitish coating to protect itself. It is quite likely that the secre- 

 tion being perhaps poisonous may have some effect in entangling 

 or disabling the prey. As mentioned by Woodwortji, Boiimig 



