270 Reed> — A Study of the Enzyme- secreting Cells in the 
and their subsequent discharge. After seventy-two hours the periods of 
secretion are not well marked. At the end of eleven days there are signs 
of degeneration in some of the epithelial cells as indicated by an abnormal 
swelling and vacuolization of the cytoplasm. After twenty-two days the 
cytoplasm is very scanty. 
II. Material and Methods. 
In my work I have attempted to study the morphology of the enzyme- 
secreting cells in the scutellum of Zea Mats and in the ‘ absorbing organ * 
of the seedling of Phoenix dactylifera . 
It has been proved by the work of Brown and Morris (’ 90 ), Hansteen 
(’ 94 ), and Griiss (’ 97 ) that the diastase produced by the scutellum of the 
Gramineae is formed and secreted by the columnar epidermal cells of that 
organ. In Phoenix dactylifera the production and secretion of enzymes 
occurs in the columnar epidermal cells of the absorbing organ (Griiss, ’ 94 , 
Puriewitsch, ? 98 ). It is to a consideration of the morphological changes that 
this paper is devoted ; the physiological changes will be made the subject 
of a subsequent study. My work was carried out at the Botanical Labora- 
tory of the University of Michigan during the years 1902 and 1903. It is 
with great pleasure that I take this opportunity of expressing my thanks to 
Professor F. C. Newcombe for his invaluable suggestions and criticisms. 
I used the large variety of Zea Mais known in agriculture as ‘ White 
Dent,’ and the seeds of Phoenix dactylifera obtained from the dates of 
commerce. The resting embryos were cut from the dry seeds and killed in 
strong alcoholic killing fluids. The embryos of different ages were 
obtained by germinating the seeds in moist sawdust or between layers of 
moist filter-paper. Light was always excluded in order to prevent any 
manufacture of food by photosynthesis. The embryos of Phoenix were 
grown in an incubator at a temperature of 30° C., those of Zea were grown 
at a temperature of 2d to 25 0 C. 
The study of fixed and stained material was supplemented by that of 
living cells in both plants. Sections of the living material were cut with 
a razor and mounted in water, or in dilute sugar-solution if they were to be 
studied for any length of time. Methylene blue in aqueous solution was 
used for intra vitam staining. In many respects the use of living material 
was not as satisfactory as one would expect, owing to the difficulties in 
identifying the different substances in the cell. It was, nevertheless, 
valuable as a check on the artificial appearances produced by killing fluids 
and other reagents. It is well known that certain methods of fixing and 
staining give characteristic appearances to the tissues upon which they are 
used, especially upon cells containing large amounts of plastic material in 
a fluid state. Many of the discrepancies between the descriptions of 
different investigators are doubtless due to different processes of fixing and 
