28 
MAMMALIAN ANATOMY 
a smear preparation 1 from the gray nerve substance of the spinal 
cord of the pig.) 
Reproductive Cells, not Forming a Tissue in the True 
Sense. — (E.g., growing ova, in place, in sections of a mammalian 
ovary.) 
D. PERMANENT MOUNTS SHOWING CELL DIVISION BY 
MITOSIS. 
Study slides (Lab. SI. Coll.) 2 which show the cells of some 
tissue in which rapid growth is in progress, where, among the 
ordinary “resting” cells of the tissue certain cells may be found 
which are in the process of mitosis. (E.g., sections through the 
growing tips of onion roots; or through the epidermis of salaman¬ 
der larvae; or surface mounts of the thin epidermis (conjunctiva) 
stripped off from the front of the eye of a salamander.) 
Use for comparison other preparations (Dem. SI. Coll.) 
showing details of mitosis. 
In each case examine first the resting cells and note the relation 
of cytoplasm and nucleus, and the presence of the deeply staining 
granules of chromatin within the latter. In the case of the 
dividing cells search for as many stages of the process and as many 
aspects of the mitotic figure as possible. Note the temporary 
disappearance of the nucleus as a distinct structure; the trans¬ 
formation of the chromatin of the nucleus into chromosomes which 
are ultimately to be split and distributed equally to the two daugh¬ 
ter cells, to eventually enter into the reconstruction of the nuclei 
of these cells; the separation of the cytoplasm into two masses 
surrounding the respective nuclei. Make suitable drawings to 
record this study. 
E. VARIETIES OF EPITHELIAL TISSUES. 
Study slides (Lab. SI. Coll.) showing a variety of epithelial 
tissues. In each case try to understand first the relation of the 
epithelium in question to the structure of the organ of which it is a 
part. Determine whether the plane of the preparation is at right 
1 For this method of making preparations for histological study, see p. 59. 
2 By the designation Laboratory Slide Collection (Lab. SI. Coll.) is meant a set of 
duplicate slides which the students use individually for study as they would do with 
their own preparations, had they the time and skill to make them. 
