SraS STiTS PROGRESS OF MICROSCOPICAL SCIENCE. 187 
long in captivity ; and (2) that it inhabits considerable depths, such 
as those of the third and fourth zones of Audouin and Milne Edwards. 
M. Vaillant has attempted to isolate the cortical substance and also 
the medullary substance, and he has made numerous sections to 
determine the nature of the process of cicatrization ; he has engrafted 
the substance of Tethea on itself, and the substance of various sponges 
of the genera Sycon, HalicJiondria, Beniera, Polymastia, on Tethea. 
He draws the following conclusions from these experiments : — 1. The 
two substances which enter into the composition of T. lyncurium are 
equally capable of reproducing each other, the isolated medullary sub- 
stance reproducing the cortical, and reciprocally. 2. The vitality of 
the cortical substance is greater than that of the medullary substance, 
a fact in relation to its histologic constitution. When detached it 
is capable of forming prolongations which can re-unite it to the 
sponge. Its contractility is also more decided than that of the cortical 
substance, if indeed this latter has any contractility at all. 3. The 
cortical portion of the sponge has a special of&ce — that of protection. 
4. Grafting from individual to individual in these species is easily 
effected, but requires some little care for its successful operation. 
6. The graft of a different genus on Tethea lyncurium has not yet 
been effected. — L'Institut, January 27th. 
The Villi of the Small Intestine. — In a paper read before the Vienna 
Academy of Sciences, Herr C. Heitzmann states that the form of the 
villi depends on the contraction of the intestinal canal, and varies 
from that of a flattened cylinder to that of a cone. The epithelial 
lining is readily detached, and this over a large extent of surface, by 
the contractions of the muscular coat. The stroma of most of the villi 
encloses cells, whose protoplasm exhibits granules of a deep green 
colour and a highly refractive nature. These he regards as chloro- 
phyll corpuscles. 
Mechanism of Flight in Insects. — M. Marey has been applying the 
graphic method to determine the nature of the process of flight in 
insects; and although the subject is hardly a microscopic one, the 
paper may be referred to as one of high interest to the naturalist. 
Some of the experiments made to determine the uniformity and velo- 
city of the movements of the wings of insects, are very interesting. 
M. Marey has replied to the three following questions : — 1. What is 
the frequency of the movement of the wing in insects ? 2. What are 
the different successive positions that the wing occupies in executing 
its complete revolution ? 3. How is the motor force which maintains 
the body in the air maintained ? The paper is abundantly and well 
illustrated, and will be found in Kobin's 'Journal de V Anatomic," 
Fevrier, 1869. 
The Movements of the Intestines. — The same journal contains an 
application of the graphic method to this question, and is full of 
interest. 
Mycoderms in the Urine of Diahetic Patients. — M. de Seynes de- 
scribes the mycoderms found in the saccharine urine of diabetic 
patients, and states that the mycoderms may be detected in urine 
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