1898] NOTES AND COMMENTS 75 



cg^, which easily glides upon the oil. On the approach of any- 

 pointed body, the yolk rises into a bubble quite similar to the cone 

 of attraction which Fol has observed before the penetration of the 

 spermatozoid into the vitellus. Sometimes it is possible to see the 

 emission of pseudopodia, which also fall back into the yolk as soon 

 as the attractive force is removed. With albumen the phenomenon 

 is still more remarkable, and if a coin, for example, is brought near 

 it, the drop is slowly distorted, attracted by the metal, and becomes 

 pear-shaped. Again, if instead of a pointed body an artificial sper- 

 matozoid approaches the yolk to a distance of four or five milli- 

 metres, as small as possible and floating on a cork, it penetrates 

 slowly, and eventually reaches the centre of the drop. The analogy 

 with the natural phenomenon is said to be complete. The oil or less 

 dense liquid represents the albumen, while the drop of yolk serves 

 for the vitelline sphere. 



The Development of a Ckane-fly 



Peof, L. C. Miall, who has so often insisted on the study of 

 life-histories as the most desirable field for the work of entom- 

 ologists, sets an excellent example by the publication (in collabora- 

 tion with Mr E. Shelford) of a paper on the larval and pupal 

 structure of a crane-fly, Phalacrocera replicata {Trans. Ent. Soc, 

 1897, pp. 343-361, pis. viii.-xi.). This larva is destitute of limbs, 

 but it bears on every segment many long and slender transparent 

 processes. These become covered with algae and other organisms, 

 and the larva is consequently very hard to distinguish amid the 

 aquatic mosses whereon it lives and feeds. The head is retractile 

 within the prothorax ; it is without eyes, but provided with a pair 

 of small slender antennae. The last body-segment bears a pair of 

 large curved chitinous anal hooks, used for grappling and loco- 

 motion ; also, on its dorsal surface, a pair of spiracles. The larva 

 was observed to come to the surface in the night to breathe by 

 means of these, but the long body-processes have probably a re- 

 spiratory function, and the creature can live submerged for several 

 days. The most noteworthy feature in the internal structure of 

 the larva is a pair of cylindrical cellular cords, of epidermal origin, 

 attached to the body-wall at the last segment between the spiracles, 

 passing into the heart by a pair of openings in the hinder wall, and 

 lying freely in the cavity of that organ, which they traverse from 

 end to end. The homologies and function of these cellular cords, 

 which seem almost unique in the animal kingdom, are left in doubt 

 by the authors, but the suggestion is made that they serve as a 

 source of reserve food material to the blood during the rapid changes 

 of the pupal stage, during which they break up and disappear. The 



