180 i-jxv^jcvcsa OF MIOROSCOPIOAL SOIENOE. 



proof i8 provisionally deficient, that all that is true of starch-flour, 

 and in a higher degree of fat, may also be asserted of other insoluble 

 bodies of finer division and, therefore, less permanence of form than 

 the starch-flour. The supposition is not in any way contradicted by 

 the discoveries of Auspitz, made in connection with his well-known 

 inunction experiments with mercury. 



Tlie Examination of Sponges under the Microscope. — In a paper pub- 

 lished last year in the ' Annals of Natiiral History,' and which is re- 

 markable, as it is the paper in which Mr. Carter, F.E.S., demonstrates 

 the true form of the sponge-cell (on which we published Prof. James- 

 Clark's paper in oiu" last number), the author gives some hints which 

 may be useful to oui- readers. He says that, for the most part, all 

 marine sjionges (save the Clionidce, which may be in deciduous shells) 

 begin to perish within forty-eight hours after they have been taken 

 from their natural habitat, although their attachment to the piece of 

 rock on which they may be growing remains uninjured ; and even if 

 they survive a little this period, they are voraciously devoured by the 

 crustaceans which may be confined with them — ^just as in all similar 

 and serial microscopical inquiries, whether free or confined, the minute 

 crustaceans are thus the most defeating agents. With the putridity 

 or dissolution of the sponge comes a development of infusoria ; and if, 

 under such circumstances, one Vibrio is seen to pass across the field, 

 the microscopist may as well give up all further research into the 

 phenomena of the living sponge. On the other hand, if the seed -like 

 body be taken from a living piece of Spongilla and placed in a watch- 

 glass with water, it may be kept under a quarter-of-an-inch compound 

 power until the young Spongilla issuing from it has gone through all 

 its phases of development from its first ajipearance to its full com- 

 pletion, which may be seen both elementarily and collectively ; while 

 during this time, having a pliu'ality of seed-like bodies growing in 

 difi'erent watch-glasses, the experiment of feeding the young Spongilla 

 with carmine or indigo, which soon points out, by its colour, the 

 position and grouping of the sponge-cells, together with the passage 

 of the particles in through the pores of the dermal sarcode, thence 

 to the ampullaceous sacs, and then the discharge of the ingesta 

 thi'ough the excretory canal system — all may be deliberately watched 

 under the same microscopic power, with so little difficulty and yet so 

 accurately, that there is no merit whatever in recording observations 

 of the whole process. It was in this way that Mr. Carter obtained the 

 data published in his paper " On the Ultimate Structure of Spongilla" 

 confirmed by similar observations on large pieces of Spongilla taken 

 directly from the tank. 



Tlie Centripetal Fibres of the Sjnnal Chord have been recently sub- 

 mitted to some experiments by Dr. Dittmar. Babbits under the 

 influence of woorara were the animals experimented on, and the 

 experiments which he carried out led him to believe that it is certain 

 that there is a system of fibres in the substance of the spinal chord 

 which, though they do not belong to the nerve roots, are capable of 

 responding to the action of direct stimuli, and can transmit the 

 impulses thus generated along the whole length of the spinal chord 



