MIOROHYDKA RYDEHI. 625 



observations. " Most important was my success in removing 

 a swelling- bud to the stage of my microscope, where its con- 

 nection with the stem of one of a colony of two hydroids was 

 unquestionable. The pup, of course, grew faster than his 

 daddy, who curled his head to one side in evident disgust, 

 the pedicle of the medusa-bud assuming the position of the 

 main stem. I made a rude camera lucida sketch at the 

 time." (The freehand drawing (fig. 15) had been made earlier 

 in the day.) 



'' On the following morning I was pleased to see that deve- 

 lopment had gone on unchecked by its removal. Wlien 

 examined that evening the tentacles had been projected to 

 nearly their full length, the expansion and opening of the 

 disc was nearly complete, and pulsations had evidently con- 

 tinued for some time. This morn (September 7th) the jelly- 

 fish was swimming about the little dish. 



'' Another important point. At the time of my last evening 

 examination, the cellular structure of the nearest hydroid 

 stem, as well as that of the pedicle of the medusa, had entirely 

 disappeared, leaving the struggling creature attached only 

 by a diaphanous cuticle almost impossible to define, within 

 which were a very few spherical floating cells and numbers 

 of detached thread-cells. This disintegration of tissues 

 serves to account for my previous failures to discern the sup- 

 porting stems, and to explain the long detention of the medusa 

 when there seemed, to be no attachment. 



"I do not mean that the Microhydra had entirely dis- 

 appeared. The stem bearing the other head had, in fact, 

 elongated, and the nearer stem seems to be re-adjusting its 

 conditions and reforming a capitulum." 



It must not be at all understood that this was the only in- 

 stance of the liberation of a medusa observed ; we saw several 

 of them, but none that so entirely eliminated the personal 

 equation of a poor memory. 



Before introducing a number of drawings illustrative of the 

 structure of the hydroid form of Microhydra ryderi, I beg 



