PLANARIA. 113 



This animal, in common with its kind, is protected from abrasion 

 by a superficial glutinous secretion investing the body, whereby it may, 

 perhaps, find the means of its suspension in the water, as if by a thread, 

 which is frequently practised. If truly so, we need not seek for any 

 secretory organ near the posterior extremity, as appearances might lead 

 the observer to conjecture. Many having congregated on a plant hung 

 in the vessel containing them, some detached themselves successively in 

 order to descend, but several individuals, at once, taking advantage of 

 a thread belonging to their neighbours, which was discernible by a magni- 

 fier, broke it from their accumulating numbers, and the load, precipitated 

 amidst the fluid, dispersed below. The glutinous matter may be drawn 

 oft' the body of the animal on quitting its hold or adhesion to any surfaces. 

 The propagation of this animal remains still as obscure to me as it 

 did many years ago ; when, from numerous specimens, I could never ob- 

 tain any progeny, though most anxiously desired. Then it was not un- 

 common that a portion of the extremity separating became a new and 

 active animal by regeneration of the higher parts. In the course of his 

 interesting treatise on the genus, * M. Duges remarks, that he could not 

 discover any sexual organization in the Planaria subtentaculata, which 

 bears some analogies to the Fountain Planaria. 



It is alike singular that the spontaneous division of the body wit- 

 nessed in the course of my earlier observations, never occurred in those 

 of later date, among 150 or 200 Planaria} taken, as above, in several suc- 

 cessive years. At the time of making them, I did not entertain any 

 doubt regarding the identity of the species. 



The animal nevertheless enjoys a vigorous reproductive faculty, 

 whereby those portions violently sundered from its body are restored by 

 new evolutions. The specimen, fig. 10, being divided into three parts on 

 September 14, the tail alone survived. Here a new head advanced far 

 in three weeks, fig. 14, and in other three, had become nearly symmetrical, 

 fig. 15, after which it survived long as an entire animal. 



* Duges, Recherches sur 1'Organization et les Mceurs des Planaries, 1828, ap. Anuales 

 de Sciences Naturalles, torn. xv. p. 69. 



P 



