84 NOTES AND MEMORANDA. 



Stentor are continued to the posterior pole of the boily, it would be 

 difficult to conceive how these fluid amoeboid processes could be 

 formed from the cortical layer to which the muscles belong. Gruber 

 saw, however, that the muscle-stripes do not converge to the pole, but 

 that a small space, which forms the posterior extremity of the body 

 (probably the disk-shaped cavity of Stein) remains free from them. 



Here the structureless sarcode appears therefore in its natural 

 state, as can be seen when the part is viewed from above. Though 

 this in different states of contraction may change very much in size 

 or even almost disappear, yet it always is there and can send out 

 pseudopodia at any moment. In this way an explanation is found as 

 to how those amoeboid processes originate, which render it possible 

 for the Stentor to attach and again detach itself at will. 



A new Method of preparing a Dissected Model of an Insect's 

 Srain from Microscopic Sections.— At the meeting of the Quekett 

 Microscopical Club of the 24th January, Mr. E. T. Newton described 

 a very ingenious method which he had devised. The brain 

 modelled was that of the common cockroach (Blatta orientalis), and 

 the method was as follows : — The brain properly hardened was cut up 

 into a consecutive series of slices, each being mounted and numbered. 

 An enlarged drawing of each section was then made with a camera 

 lucid a, and these drawings transferred to pieces of wood of a thickness 

 proportionate to the thickness of the sections, and then cut out with a 

 saw. By piling together in their relative positions this series of slices 

 of wood and ti'imming off the angles, a model of the external form of 

 the brain was produced which can be taken to pieces so as to show the 

 drawings of the sections upon their faces. The series of slices which 

 make up the right half of the brain were then taken and the more 

 important structures in each cut out like a child's dissected map puzzle. 

 The corresponding structures were taken from each slice and fixed 

 together in their relative positions, in such a manner that the whole 

 may be fitted together, and when desired the more important jjarts 

 may be, as it were, dissected out. The President (Professor Huxley) 

 highly commended the ingenuity of the method and the manner in 

 which it had been given effect to in the modjl — an expression of 

 approval which was fully endorsed by the meeting. 



The Relations of Rhabdopleura. — This singular Polyzoal genus 

 was the subject of a communication by Professor Allman, Pres. L. S., at 

 the meeting of the Liuueau Society of the 19th December. He main- 

 tains that the endocyst, hitherto supposed absent, is really represented 

 by the contractile cord which seems to take the place of the funi- 

 culus in the fresh-water Polyzoa. In Rhabdopleura the endocyst has 

 receded from the ectocyst, and its wall ajjproximation and nearly com- 

 plete obliteration of cavity has become changed into the contractile 

 cord. Anteriorly it spreads over the alimentary canal of the polypide, 

 to which it becomes closely adherent, and here represents the tenta- 

 cular sheath. Posteriorly the endocyst undergoes greater modification, 

 the contractile cord becomes chitinized, and converted into the firm 

 rod which runs through the stem and branches over all the older parts 

 of the colony, and which still presents in its narrow lumen a trace of 



