86 Part I11.—Twenty-third Annual Report 
Additional measurements of lobsters of different stages :— 
Date. Stage. Measurements. 
Mm. 
Sept. and Oct. 
1902. iVecZoea- 15 Abr aOR ee Go: 
i M. 1521s Patel 
1°67" 126: 
Sept. 1902. +1 155i! 1-5ds, 62 dso 
187 eA 
DeEatTH oF THE Youna Lossters, First Youna Stace AND LATER, 
The majority of the young lobsters reared at the Laboratory have died 
shortly after casting. Asa rule, the death took place gradually, as if a 
disease had seized them immediately on casting. ‘The lobster became at 
once sluggish, moved about with difficulty, and simply ebbed away. 
October 23rd (No. 3).—One of the young lobsters cast, but became weak 
immediately after, and was hardly able to move a limb. It was removed 
to a larger vessel with a good supply of water, and it seemed to be 
reviving on the 28th. On October 31st it was livelier ; it could move 
its pleopods, but seemed to be paralysed in the thorax ; a faint movement 
of the antennules was noticed. It hada large swelling on its left side at 
the hind part of the carapace. It was dead on November 3rd. 
On October 31st (No. 5) a lobster that had not cast recently was seen 
to be almost dead ; there was just a little movement detected in the last 
pleopod. On November 3rd it was dead and covered with a fungoid 
growth. 
On November 3rd (No. 6) a lobster which was half-cast was found as 
if dead. No movement was noticed. The lobster was torn asunder, and 
it was then seen that life still remained, as vermiform movements of the 
organs were detected, A puff of white fluid material was squeezed from 
the anterior half of the body, and examined by means of the microscope. 
It was seen to consist of great numbers of infusors of various kinds, the 
majority being very small and roundish in shape; others were long, 
pear-shaped. Some were progressing with an eel-like motion. Sporo- 
spheres consisting of a mass of minute infusors were made out. The 
water in which the lobster was had no infusors in it when a drop was 
examined, 
The death of the young lobsters is, without doubt, due to the rapid 
development in them of these infusor parasites. It is possible that during 
the casting process the infusors may gain admittance to the body, and 
their rapid multiplication there results in the death of the host in a few 
days. 
One lobster, the largest reared, measuring 1 inch (2‘5cm.) in length, 
reached that size by a cast on October 31st 1904. On November 3rd it 
appeared to be dead. On examination a little movement was detected in 
its limbs. It was removed to a large jar, but did not recover, 
~ 
- > 
