Larva of Chaoborus Crysta llinus (de Geer). 
363 
the outside — stained very heavily , indicating this is fat; hsema- 
toxylin being one of the fat stains. On the inside there is a layer 
of cells. (PI. XIX., fig. 31.) 
3. We placed a well-fed larva in glass tank. To this was 
added some chopped -up larvae — the top of the tank was plugged 
to avoid evaporation. This was kept in a room with night and 
day temperature of about 65° F. The water soon became foul and 
milky in appearance. At the end of ten days the creature was 
still vigorous and lively. 
4. E. J. Sheppard noticed when cutting sections of this larva 
that the integument had a tendency to break up in a similar 
manner to that of the chitinous coat of the flea, of which creature 
he had cut many hundreds of sections. 
Other references to this question are given in Frankenberg’s 
paper, from which we have extracted the following details: — 
“ I refer to the power of resistance of the apparently delicate 
body wall of Corethra , which is, contrary to expectation, quite 
impervious. 
“ (A) It cannot be specially pervious to water, for animals 
which are brought into pure glycerine shrink only after several hours. 
“ (B) The permeability for air cannot be so great as has always 
been thought, otherwise the gas bubbles produced — as described in 
another part of the paper — which create such high pressure in the 
body of the creature, must be dissolved again more quickly in the 
surrounding water after readjustment of the normal pressure. 
“ (C) It is very extraordinary what small effect the usual 
narcotizing media, such as orthoform-aethylethane, etc., have on 
the larvae. 
“ (D) It is remarkable that Corethra hold out in dirty filthy 
water after all the other plankton have long been dead. 
“(E) Larva placed in 53 p.c. alcohol, Xov. 14, 1913, at 
3.50 p.m., sinks to the bottom but moves vigorously — at 4.30 p.m. 
convulsive quivers — 5.0 p.m. motionless — heart and intestine not 
moving. Animal now brought into water, Xov. 15, 9.20 a.m. — 
vigorous convulsive movements of the muscles, intestine moves 
feebly. Xov. 17 — completely recovers — lived until Jan. 1914. 
“ (F) Intra-vitam staining is almost impossible. Employing 
a strong solution of methylin blue — only the middle part of the 
intestine and the onocytes took the colour.” 
T. Charters White ( 8 ) also points out : — “ Osmic acid of J p.c. 
strength does not seem to affect it injuriously ; even acetic acid 
largely diluted in water does not seem to act prejudicially to an 
existence extending over some hours.” 
We have kept the larva in boiled water contained in a sealed 
bottle for one month. It was fed once only during that period by 
transferring it to fresh pond water containing a supply of Chydorus 
sphericus. 
