XIII 



COCOONS 



365 



opinion of D'Udekem being that they were the product of 

 certain glands developed in Lumbricus at the breeding season, 

 which he thence called the capsulogenous glands. It is more 

 probable that these glands, which have been up to the present 

 but little investigated, are the seat of the formation of the 

 albumen which is found within the cocoons. The cocoons are 

 deposited at varying depths in the ground, or on the surface. 

 Among the aquatic genera they 

 are often attached to aquatic 

 plants. The process of forma- 

 tion has been carefully watched 

 by Vejdovsky 1 in the genus 

 Rhynchelmis. The worm throws 

 off the cocoon over its head, 

 crawling backwards to free itself 

 therefrom. The eggs, sperma- 

 tozoa and albumen, reach the 

 interior of the cocoon as it 

 passes over the orifices of the 

 respective ducts. Out of the 



numerous egffS which a single Fig. 194. Cocoons of Lumbricidae. (After 



00 Vejdovsky.) A, Lumbricus rubellus, 



COCOOll Originally contains, Only nat. size and x 3 ; B, AUurus, nat. size 



a few, sometimes only one, ^d x Q ; c, Alioiobophora foetida, nat. 



J size and x 3. 



reaches to maturity. Among 



the Enchytraeidae, however, quite a large number of young 

 emerge from a single cocoon. The development of all the Oligo- 

 chaeta is direct, there being no free larval stage. It seems to 

 be the rule for a process of fission to take place in the embryos 

 of Allolobophora trapezoides 2 at least, according to the observa- 

 tions of Vejdovsky, in warm weather. In cold weather he found 

 in each cocoon as a rule single embryos, and only 10 per cent of 

 double embryos. 



Habitat. Earthworms are found in almost every part of 

 the world where they have been looked for. They occur far to 

 the north, in Siberia and Nova Zembla, 3 while South Georgia 

 and Kerguelen mark their southern limits. From arid tracts 

 of country they are naturally absent, and also, which is more 



1 Entivickelungsgeschichtliche Untersuehungen, Prag, Heft i. 1888, p. 33. 



2 See Kleinenberg, Quart. J. Micr. Sci. xix., 1879, p. 206. 



3 Both Col. Feilden and Mr. Trevor-Battye found specimens in Kolguiev. 



