630 Destruction of Obnoxious Insects by Fungoid Growths. [Sept’r, 
numerous along the stem. A dash shows that the organs of the 
typical medusa are wanting. 
It will be seen that I do not homologize the stem of Agalma 
_ with the stem of a fixed hydroid, but with the proboscis of a 
medusa. The Siphonophore are not free swimming hydroids, 
but medusz with polymorphic individuals budding from it sitai- 
larly to the condition in Zizsia, These buds are not zooids 
but physiological and morphoiogical individuals. I cannot follow 
Leuckart when he considers, however, that every bud is an indi- 
vidual. Three buds, the scale, the polypite and the tentacle 
together make one individual. Upon this subject we must look 
to embryology for light. 
——0: 
DESTRUCTION OF OBNOXIOUS INSECTS BY MEANS 
OF FUNGOID GROWTHS. 
BY PROF. A. N. PRENTISS. 
| Concluded. 
Experiment No. 3—May 10 —A calla lily has become infested 
with aphides and red spider. The whole plant is carefully washed 
with a sponge except a small spot on one leaf wheré twenty-seven 
aphides are left, and a’similar spot on another leaf where about 
twenty red spiders are left. The whole plant is sprinkled with 
domestic yeast, care being taken to thoroughly drench both the 
aphides and red spiders. The plant is covered by a bell jar which 
rests upon a ring of cotton batting, so as to shut the plant off 
from the approach of insects or spores from without, and prevent 
the escape of those within. Under the bell jar are placed two cups 
` of actively fermenting yeast. 
May 14.—The plant carefully examined. No dead aphides to 
be found. A number of cast-off skins are seen. The aphides 
are well scattered over the plant, but more than the original twenty- 
- seven can be counted. The red spiders are also scattered so that 
the number cannot be ascertained, Several living but no dead 
‘ones are seen. That the spiders should have decreased in num- — 
: bers might be expected from the moisture of the yeast independent 
of the Torule. _ ; : 
Experiment No. 4—April 8.—Selectegl a thrifty rose geranium, — 
about ten inches high, that had by count seventy aphides upon 
it, collected mainly upon the tender shoots. a 
_ The yeast is prepared by dropping pieces of compressed yeast 
_ cake, bought at the grocer’s, into Pasteur’s fluid with sugar. In 
