534 Reed . — The Value of Certain Nutritive Elements 
By the use of stained preparations I was able to study the form of the 
nuclei in cells which showed signs of injury. I was unable to observe the 
shrunken nuclei which Bokorny (’95) observed under similar conditions. 
On the contrary the nuclei presented an unusually firm, even contour, 
because most of them had lost the enveloping layer of protoplasm with its 
radiating strands. 
On account of the peculiar effect which the absence of calcium had 
upon the development of sexual organs on the prothalli of Gymnogramme 
sulphur eum , it may be of interest to note the effect of the absence of 
magnesium. The spores of that fern when sown upon the surface of 
a nutrient solution germinated and grew very well. At the expiration 
of three months there were large numbers of well-developed prothalli 
on these solutions. A considerable quantity of starch was present in the 
younger cells on the lateral lobes, but less was present in the cells near the 
apical notch. Archegonia were quite numerous upon the ventral surface of 
the prothalli, several archegonia being found near the apical notch on 
almost every prothallus examined. The small amount of magnesium 
originally present in the spore of the fern was evidently sufficient for quite 
extensive growth in this case. 
The cultivation of Vaucheria in deficient nutrient solutions is, generally 
speaking, rather difficult. Many of my attempts met only with failure, but 
in the case of magnesium-free solutions, I met with somewhat better 
success. Material was used which had grown for two months in the 
laboratory. The filaments appeared to be in good growing condition, 
containing both chloroplasts and oil drops throughout. A few of the 
filaments were beginning to form oogonia, and judging from their form 
the species seemed to be V. gemmata. The cultures stood upon the 
sill of a west window, at room temperature from January 17 to February 7 . 
Upon the last-named date I found that the filaments in the magnesium-free 
solutions were entirely without oil globules, although oil globules were 
abundant in the filaments in the control solutions. Otherwise the filaments 
in the magnesium-free solutions appeared perfectly healthy and not injured. 
Filaments taken from the same source were growing in solutions lacking 
calcium salts without showing any diminution in the number or size of the 
oil globules they contained. It seems that there is no escape from the 
conclusion that there is an intimate relationship between the presence 
of magnesium and the formation of vegetable oils. Such a relation was 
suggested by Loew (’99), and he called attention to the fact that analyses 
show that oil-containing seeds like those of flax and cotton contain much 
more magnesium than the starch-containing seeds, like those of the cereals. 
Aso (’01) has published analyses of the spores of Aspergillus oryzae which 
show that those spores contain a moderately large amount of magnesium. 
This fact seems of importance because we know that the spores of the Fungi 
