1 92 RAMBLES AND REVERIES. 



portion will develop into a perfect polypite. The 

 usual method of reproduction, however, is by budding, 

 an example of which is seen on the left of our 

 illustration (Fig. 48), and also by means of eggs 

 which are deposited in winter. 



Perhaps the most curious fact about the hydra is, 

 that it possesses certain arrow-headed stings, by 

 means of which it is able to benumb such minute 

 organisms as it wishes to capture for food. 



These stinging threads may be got for examination 

 by cutting off one of the tentacles, and looking at it 

 through an objective of one-sixth or one-eighth focal 

 length, giving a magnification of, say, three to four 

 hundred diameters. Then let the light pass through 

 it obliquely, and there will be seen all around the 

 edge a number of small cells or capsules, from which 

 a very fine thread will be emitted. These stinging 

 organs are similar to those possessed by sea- anemones; 

 and bathers have occasionally been -made aware of 

 the fact that the Medusa jelly-fish has the same 

 kind of weapons. 



The hydra is remarkably simple in structure 

 and in organisation. The whole body is composed 

 of similar substance called sarcode, in which is 

 enclosed a colouring matter. Every part has a high 

 contractility, and though the creature is eyeless it 

 is very sensitive to light, as the microscopist soon 

 discovers. The outer portion of the sarcode is 

 probably a trifle denser and harder than the inner, 

 and hence the two words ectoderm and endoderm 

 are used to denote the two integumentary layers. 



The hydra being done with, it was time to stop 



