74 



THK INDIVIDUALITY OF 



the medusa itself. Now it has been asserted that the eggs of a 



most deceptive, as regards its individualistic character, of all Hydroida. During 

 the spring, there may be found, in the rocky tide-pools of our sea-coast, minute 

 tufts of a tender, deep orange color, resembling some of the 

 more delicate sea- weeds, at first sight. The little stems, of 

 about one sixth to one quarter of an inch in height, appear 

 to be diverse in kind among themselves to a manifold decree. 



O 



The two most striking diversities are those of height; the 

 more elevated stems (fig. 38, I) bristle with slender needle- 

 shaped bodies (t), and usually in point of numbers are one 

 \d in every six of the two kinds. The shorter kinds are totally 

 devoid of the bristling organs of the taller ones, and at the 



m 



MI 



Bt 



end vary from a smooth, club-shaped form (II) to a more or 

 [0 less globose shape (IV) with diverse degrees of knottiness 

 (III and IV). All these various shapes and proportions are 

 united in a colony of compound individuals by a creeping 

 stem (st), which runs over the rocks, and forms the means 

 of attachment for the whole group. The tallest forms mi<rht 

 be compared to the workmen in a hive of bees, as their 

 office is to obtain food for the whole colony, whilst the more diminutive sort, sub- 

 serving the means of reproduction, would be the queen-bees and their immediate 

 attendants. The feeders, or sterile hydras (I), consist of slender cylindrical 

 shafts which taper at the free end (m), and likewise suddenly narrow appreciably 

 where they join (s) the creeping stem (st). The mouth (m) is at the tip, and 

 leads directly into a simple, narrow digestive cavity which extends to the base (s) 

 of the stem, and thence in every direction throughout the creeping stolon (st) 

 and into the fertile individuals (d, d l ). About one half of the sterile hydra, from 

 its tip downward, is endowed with twelve to fifteen needle-shaped feelers ({) 

 arranged in a spiral about the shaft. The body of this, as well as the creeping 

 stolon, and the stems of the fertile kind, are composed of two walls (o, in), and 

 the whole is covered by a thin, filmy, parchmenty, shrivelled envelope (p, p), 



continuation of p over the planules and the reproductive capsules ; o, outer, and 

 in, inner walls of the stems ; o', o 2 , the wall of the reproductive organs ; c, the 

 cavity of the same ; pr, pr*, pr*, the proboscis-like body of the same ; op, the 

 fissures through which the planules (pi) escaped from the reproductive medusoid ; 

 pi, pP, planules on the outside of III, IV; pH, pP, planules within the same; 

 eg, the eggs; g, the germinal vesicle of the egg. Original. 



Fig. 39. Rhizogeton fusiformis. Ag. A male reproductive capsule. st,s,p, 

 o, ol, in, d, pr, the same as in fig. 38 ; in*, base of pr\ ml, cavity of the capsule. 

 Original. 



