DEPARTMENT OF EMBRYOLOGY. 95 



a drop of culture medium to which an increased amount of calcium 

 has been added. From a microscopic study of the contracting cells 

 it became apparent that the cytoplasm, which is quite elastic, plays 

 the most active part in the contraction; while, so far as could be seen, 

 the nucleus, the nucleolus, and the chondriosomes take only a passive 

 part. There are no myofibrils present in these living, contracting 

 smooth-muscle cells. In the act of contracting the cytoplasm is 

 accumulated at a given point at the expense of the surrounding region, 

 forming a thickened and folded mass called the contraction node. 

 Coincident with the contraction of a muscle-strand there usually 

 occurs a swaying or pendular movement of its substance, so that it 

 is thrown in a curve, this movement being more pronounced during 

 relaxation than during contraction. 



The effect of a group of vital stains upon the eggs of Cerehratulus 

 lacteus, Echinarchinius parma, and Lophius piscatorius has been 

 studied by Margaret Reed Lewds, with the object of determining the 

 effect of such stains upon the fertilization of eggs and the later develop- 

 ment of the embryos, and especially as to whether they are in reality 

 vital stains which vdW stain the granule of a cell without injurj^ to 

 either the cell or the developing embryo. IVIrs. Lewis found that the 

 spermatozoon and the unfertilized egg are both sensitive to the toxic 

 effect of all stains, especially janus green. After the eggs are fer- 

 tilized they become progressively more resistant, although a suf- 

 ficiently strong solution of any of the stains would cause the death of 

 even the older embryos. If used in weaker solutions brilliant cresyl- 

 blue 26 and neutral red proved to be true vital stains, the granules 

 of the cells being deeply colored wdthout interrupting the development 

 of the embryo. On the other hand, it was found that janus green, 

 under such circumstances, is not a vital stain, for not only did it 

 usually prevent fertilization of the egg, but also in every case where 

 the solution of the stain was of sufficient strength to color any of the 

 granules of a cell it killed the embryo. It is interesting to note that 

 individual stains show an affinity for certain types of granule. Two 

 definite types are stained — one by janus green, the other by neutral 

 red, those stained by the former probably being the chondriosomes. 

 Similar results are obtained by the apphcation of the same dyes upon 

 spermatozoa in which the middle piece or chondriosomal body is 

 stained b}^ the janus green, while a granule on one side of the head of 

 the spermatozoon is colored 'ttdth neutral red. In addition to these 

 two types of granules, there are the yolk or fat globules, which do not 

 stain in the hving embryo, either with neutral red or janus green. 



Investigations regarding the character and distribution of chon- 

 driosomes have been carried on by E. V. Cowdry, N. H. Cowdry, 

 and J. Duesberg. The comprehensive paper on this subject by Pro- 

 fessor E. Y. Cowdry vnll be reviewed in our next report. The relation- 



