Mat 15, 1908] 



SCIENCE 



779 



rent work of the Department of Comparative 

 Anatomy, was held at the Harvard Medical 

 School on the evening of April 7. A brief 

 paper was presented by every member of the 

 department, and by Dr. Meigs, who has used 

 the laboratory for the histological portion of 

 his studies concerning the physiology of 

 muscle. After the meeting there was an ex- 

 tensive demonstration of preparations illus- 

 trating the papers presented, and the labora- 

 tories were open for inspection. Serial sec- 

 tions of the eggs of the Mexican axolotl were 

 exhibited, showing all the important stages 

 of maturation and fertilization; eighty of 

 these series have recently been added to the 

 embryological collection. They were specially 

 prepared by Dr. J. W. Jenkinson. From the 

 following abstracts it will be seen that a con- 

 siderable variety of scientific topics was dis- 

 cussed, all of which are of medical interest. 



Dr. E. B. Meigs described the histological 

 differences between relaxed and contracted 

 smooth muscle fibers. 



A number of physiologists have supposed 

 that muscular contraction might be the result 

 of the passage of fluid from one part of the 

 muscular tissue to another, and recent com- 

 parisons between histological preparations of 

 relaxed and contracted striated muscle indi- 

 cate that, during the contraction of this form 

 of muscle, fluid passes from the sarcoplasmic 

 spaces into the fibrillae or sarcostyles. 



The present investigation consists in a 

 comparison between preparations of uncon- 

 tracted and contracted smooth muscle. The 

 results indicate that in smooth muscle also 

 there is a passage of fluid from one part of 

 the tissue to another during contraction, but 

 that the movement in this case is opposite 

 in direction to that which takes place in the 

 case of striated muscle; the contraction of 

 smooth muscle seems to be accompanied by a 

 passage of fluid from the contractile cells to 

 the intercellular spaces. 



The histological results in the case of both 

 striated and smooth muscle are in harmony 

 with the reactions of the two tissues to swell- 

 ing reagents and their opposites. Striated 

 muscle immersed in distilled water, or in 

 various other reagents which are absorbed by 



it, slowly goes into contraction; and pieces 

 of muscle which have been caused to contract 

 in this manner may be made to lengthen 

 slowly by immersion in reagents which ab- 

 stract water from them. Both kinds of re- 

 agents have exactly the opposite effects on 

 smooth muscle. 



Dr. L. W. Williams discussed the noto- 

 chordal origin and the histogenesis of the 

 nucleus pulposus. The notochord of the 

 young mammalian embryo is a continuous rod 

 of uniform diameter. It is composed of 

 clearly defined cells surrounded by a thin 

 outer, and a thick mucin-containing irmer 

 sheath. The deposition of inter-cellular sub- 

 stance in the embryonic vertebral cartilage 

 squeezes the notochord into the intervertebral 

 discs, where it forms the nuclei pulposi. 

 Within the vertebrae, the notoehordal tissue 

 degenerates. The sheaths after becoming 

 calcified are finally destroyed by bone-form- 

 ing tissue. Within the nucleus pulposus, the 

 loss of cell-walls converts the notoehordal 

 tissue into a syncytium with mtiein in its 

 meshes. It closely resembles embryonic con- 

 nective tissue. The notoehordal nuclei mul- 

 tiply rapidly, by mitotic division. The inter- 

 cellular substance increases in volume and 

 finally separates the syncytium into smaE 

 vacuolated masses of protoplasm, similar to 

 fat cells. Each cell is spherical and usually 

 has two nuclei, which lie in a small amount 

 of cytoplasm separating two or more large 

 vacuoles. It was shown that the notochord 

 in man normally has a sinuous course in the 

 base of the skull, and that chordoma usually 

 occurs at the points where the notochord 

 comes nearest to the upper surface of the 

 bone. 



Dr. V. E. Emm el presented some results 

 of his studies in regeneration and growth. 

 According to Conklin's hypothesis inverse 

 symmetry in moUusca and perhaps also situs 

 inversus in man are due to an inverse organi- 

 zation of the egg, corresponding with matura- 

 tion at opposite poles. It does not accord 

 with this theory that until the fourth molt 

 the large crusher claw of the lobster may be 

 made to develop on either the right or the 

 left side. In the larval lobster the first pair 



