296 PROGRESS OF MICROSCOPICAL SCIENCE. 
the lymphatics of tendons, fascie, and serous membranes can very 
conveniently be injected by flexing and extending these parts. The 
joint of a newly killed dog was filled with a coloured fiuid, and 
the limb flexed and extended, but no colouring matter entered the 
lymphatics. This would seem to show that absorption from the 
synovial surface takes place in a way different from that which 
obtains in the case of serous membrane. By the puncture method, 
however, Tillmanns easily succeeded in injecting with a 0°5 per cent. 
solution of silver or soluble Berlin blue, a very rich network of 
lymphatics lying immediately under the epithelium and also in the 
subsynovial connective tissue. This he did in the large joints of 
the ox and horse. The superficial lymphatics lie directly under the 
epithelioid layer, deeper than the finest capillaries, but superficially 
to the large arterial and venous branches. The author finds that the 
blood-capillaries do not project bare into the joint, but are covered 
by the epithelioid layer. No lymphatics were found in the villi of 
the joints. The superficial subepithelioid lymphatics communicate 
with very wide vessels lying in the subsynovial tissue, where the 
lymph-vessels are very numerous and not unfrequently surround 
the blood-vessels. The vessels can be most easily injected where the 
synovial membrane joins the base or cartilage. No lymphatics pass 
from the synovial membrane, either into the subjacent bone or carti- 
lage. The microscopic structure of the lymphatics was studied by 
Stirling’s method, viz. digestion in artificial gastric juice. It seems 
that the epithelioid lining of the lymphatics is directly continuous 
with the elastic tissue of the adjacent tissue, thus fixing the lym- 
phatics. The lumen of the vessels will thus be kept patent by the 
elastic fibres, and may even be dilated when the fibrous tissue becomes 
swollen. This bears out some suggestions already made by Ludwig 
under normal circumstances. 
Remarks on the Structure of Precious Opal.—Professor Leidy, 
according to ‘Silliman’s American Journal’ for April, has an article 
in the ‘ Proceedings of the Academy of Natural Sciences of Phila- 
delphia’ for 1876, p. 195, on the microscopic structure of the opal of 
Queretaro, Mexico. 
Structure of the Red Blood-corpuscle of Ovipara.—Mr. Gulliver 
sent a note on this subject to a late meeting of the Hast Kent Natural 
History Society. It is conceivable, he wrote, that there may be an 
essential difference between the corpuscles of batrachians and fishes ; 
so that, granting the truth of his own and Mr. Hammond’s obser- 
vations on the presence of the nucleus in the living corpuscles of this 
class, the validity of Professor Savory’s observations on the absence 
of the nucleus of the living corpuscles of frogs and newts would not 
be necessarily destroyed. And then the question would only be like 
that which was so much agitated upwards of a quarter of a century 
ago, concerning the structure of these corpuscles throughout the ver- 
tebrate sub-kingdom. At that time one party, following Hewson, 
declared that the nucleus is quite distinct; while another party, with 
