HARDWICKE'S SCIENCE-GOSSIP. 



17 



Structure and Development of the Teeth." The 

 paper formed a concise resume of the present state of 

 our knowledge of the structure and development of 

 the teeth. It was freely illustrated by microscopic 

 specimens and diagrams ; many of them refer to the 

 earliest condition of the teeth. Mr. Paul called 

 attention to the value of studying the embryonic 

 condition of the tissue, and showed the developmental 

 relations between hair, feathers, horns, hoofs and 

 teeth. He then traced up the growth of the necessary 

 and permanent teeth from the first appearance of the 

 enamel germ of the sixth week to the mature state, a 

 discussion of the structure of which occupied the 

 concluding portion of the paper. The President 

 accorded the thanks of the Society to Mr. Paul for 

 his most instructive and well-illustrated paper. 

 A discussion followed in which the President, Rev. 

 W. Banister, G. F. Chantrell, Esq., Dr. Nevins, and 

 others took part. The meeting concluded with the 

 usual conversazione and microscopical exhibition. 



Polariscopes. — It has struck me that some of our 

 economical microscopists, who have wished for a 

 polariscope, but have been unable to obtain one on 

 account of the expense, may have invented a make- 

 shift one for that purpose, and as I am wishing very 

 much for one, I should be glad to know if anybody 

 has ever made such an one, and if so, how he made it, 

 worked it, and kept it? — Economy. 



The Quekett Microscopical Club. — We have 

 received No. 41 of the " Journal " of this popular 

 and ever-green society. It contains the following 

 papers : — " On a Method of Resolving Diatom Tests," 

 by Adolf Schulze ; "On the Anatomy of Actinia 

 mesembryanthemitm" by F. A. Bedwell ; " On the 

 Reproductive System of some of the Acarina," by 

 A. D. Michael; "On Staining Sections of Animal 

 Tissues," by J. W. Groves ; " On some Improvements 

 in Microscopical Turn-tables," by C. Spencer Rolfe, 

 and lastly (but not leastly, for the discourse, if short, 

 is most pithy and suggestive), we have the address of 

 the President of the Club, Professor Huxley. 



ZOOLOGY. 



DAPHNIA VETULA. — Whilst examining one of 

 these water-fleas, I noticed a small one inclosed in 

 the body of the larger, which was of course living 

 {the larger one). The smaller one had no apparent 

 motion of life to me. I transferred it to filtered water 

 to clean the intestine as recommended by Davies, 

 and examined it before putting it to soak in dilute 

 alcohol and glycerine, but did not see the small one. 

 Do water-fleas bring forth their young alive, as in the 

 plates I have seen of them I can only see what 

 appear to be eggs, in the body where I saw the 

 young one ? — J. M. 



Phosphorescence of Earth-Worms. — Is it 

 generally known that the earth-worm (Lumbricus 

 terrestris) is sometimes highly phosphorescent ? Pro- 

 fessor Paley does not mention this in his able and 

 exhaustive article. I disturbed one the other night ; 

 it became very luminous and left a trail of light behind 

 it as it passed along the ground. — F. W. E. Shrivett. 



Mistaken Instinct.— In the April part of 

 Science-Gossip there is a short note on mistaken 

 instinct. The following may perhaps prove interest- 

 ing to some readers. In July last, one fine afternoon, 

 as we were watching my bees carrying in pollen, one 

 of them separating from the others alighted on some 

 pretty blue artificial flowers in the bonnet of a lady 

 who was looking at them ; tried each flower carefully 

 for honey, and, of course, finding none, flew away, no 

 doubt much disgusted. The bee must have been 

 attracted by form and colour ; the flowers were not at 

 all natural, but gaudy red anthers and blue stamens. — 

 Fred. W. E. Shrivell. 



Mistakes made by Instinct. — In the July 

 number of Science-Gossip, I communicated the case 

 of an egg of Anthocharis Cardamines being laid on 

 the caducous sepal, instead of the pedicel, of the flower 

 of the food plant by the insect in captivity. I 

 subsequently met with several instances of the same 

 thing occurring under natural conditions. Errors in 

 instinct through the laying, or [mis-laying, of their 

 eggs by insects at wrong times or in wrong places were 

 well known to the older entomologists, as the following 

 interesting passage from Degeer abundantly proves. I 

 quote from the German translation of Gotze (Ab- 

 handlungen zur Geschichte, &c, vol. ii. part 2, page 

 241, plate 35, figs. 12 and 13). He has been 

 describing a saw-fly which spins a double cocoon. 

 Inside one of these double cocoons, with its head 

 sticking out of its own coarctate pupa-case, he found 

 a dead dipterous parasite of the saw-fly; and he 

 ascribes its death to a mistake of the parent fly in 

 laying her egg on the false caterpillar of the saw-fly 

 when the latter was too advanced in its growth. "Its 

 fate," he says, "was a consequence of the mother's 

 oversight, which seems to have laid her egg too late 

 on the false caterpillar, so that the larva proceeding 

 from it could not attain to its full size before the saw- 

 fly caterpillar must prepare for its transformation, and 

 consequently, unwittingly let itself be shut up in an 

 everlasting prison. It had indeed gone on to devour 

 the caterpillar. It had changed to a nymph within 

 the red cocoon; but when it became a fly it could 

 not make its way through the double cocoon of the 

 saw-fly, and must consequently perish. Thus the 

 mother fly had erred in laying her egg, a thing that is 

 not usual among insects, which on every occasion, 

 and especially in the propagation of their species, 

 display always so much diligence and foresight." To 

 this, however, the translator adds in a note : "Never- 

 theless, examples and instances occur in more than 



