E. W. BERGER ON THE CUBOMEDUS^E. 41 



Most of my series were cut 4 (i in thickness. All in all I cut 

 sixty-five clubs besides making some maceration preparations from 

 material preserved for that purpose. These sixty-five series represent 

 material from fourteen bottles. As a whole, my material was good, 

 but the material from one bottle was decidedly superior for showing 

 the axial fibers of the prisms and pyramids of the retinal cells. 

 This shows the advantage of plenty of material. It will be evident 

 that I had plenty of material. 



I found iron-haematoxylin the most satisfactory stain. I stained 

 for a shorter or a longer time one-half to several hours and longer 

 and then washed out the sections until under a low power of mag- 

 nification they appeared quite unstained, the nuclei and a few other 

 parts only appearing darkly stained. 



Depigmentation I practiced but little. I obtained many of my 

 series almost wholly unpigmented, especially those I cut last. Others, 

 of course, were very heavily pigmented. I am not certain but that 

 alcohol slowly dissolves out the pigment after a long period of 

 preservation. Slight variations in the technique of killing and pre- 

 serving may also, perhaps, determine the stability or solubility of the 

 pigment, as, of course, also the condition of the pigment at the time 

 of killing. 



Anatomy. For a short epitome of the anatomy of a Cubomedusa 

 and of a Cubomedusan sensory club see p. 2 of the Introduction. 



The Distal Complex Eye General. The distal (larger) complex eye 

 (Fig. 7) and the proximal (smaller) complex eye (Fig. 13) are so 

 named to distinguish them from the lateral simple eyes of the clubs. 

 The distal complex eye consists of the following parts : a cellular 

 cornea, continuous with the epithelium of the sensory club ; a cellular 

 lens (externally cellular and internally often quite homogeneous) 

 immediately beneath the cornea ; a homogeneous capsule just internal 

 from the lens, and evidently a secretion from the lens cells; a 

 vitreous body composed primarily of prisms and pyramids just 

 beneath the capsule ; and a retina of pigmented cells, with sub- 

 retinal nerve tissue, ganglion cells and fibers. To my knowledge 

 all observers (except Carriere, who missed the capsule) are quite 

 agreed on the anatomical structure of the distal complex eye as also 

 4 



