BY R. .T. TILLYARD. 393 



removal froin the vegetable tissues had seiiously attectetl llie 

 emhiyonic development of .Series A. T at once introduced a 

 considerable amount of fresh tap-water into the dish, fearing 

 that otherwise I might not succeed in obtaining any larva? at all 

 from this Series. 



On March 28th, two lai'v;e had hatched out in Sei'ies C, and 

 were normal and healthy. On March 29th, three more hatched 

 out in Series C, and one in Series B. This last was transferred 

 to the Petri dish, where it lived for three days. On March 

 oOth, two more larvse hatched from Series C, two from Series B, 

 and two also from Series A. But these latter were both dead 

 when I found them, though they could not have been hatched 

 more than three hours before (i.«., the time of my previous 

 examination of the dish). 



It was now necessaiy to spend every available moment watch- 

 ing Series A. For the four days, March 31st to April 3r(l, T 

 spent the whole of daylight ami portion also of the nights in 

 watching these eggs, only desisting for the shortest possible 

 intervals for meals and rest. On March 31st, I selected in 

 particular one embryo with a very slow but fairly regular })ulse 

 of about 20 to the minute, and watched it for four hours. I 

 then desisted for half an hour's rest, and, on returning, found that 

 this egg had hatched, and the larva was pi-actically moribiuid. 

 The next day, I watched tlie eggs for fourteen hours, selecting 

 four especially that showed a fairly regular pulse. But I met 

 with no luck, as not a single egg hatched on that day. 



On April 2nd, I got up very early, and was rewarded by find- 

 ing one of the four eggs above mentioned _/?t6'^ in pr-ocess of hatch- 

 in</. I was just in time to see the pronymph pass out from the 

 egg-shell. The cephalic heart was acting very sluggislily; in 

 fact, I had barely time to locate it before it subsided. The pro- 

 nymph failed to pass completely out of the egg-shell, and re- 

 mained with the last three oi' four abdominal segments inside it. 

 The pulse of the dorsal vessel was 52 pei' minute. The larva 

 made repeated attempts to remove the pronymphal sheath, by 

 moving its head up and down, and also by forcing its midgut 



