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1887. | BOTANICAL GAZETTE. 41 
light should be about twenty inches from the microscope, and the globe 
sufficiently supported so as not to oscillate. The light obtained is bright 
but not dazzling, and of a soft green color that is extremely agreeable to 
the eyes. A screen of some kind should be used to protect the eyes from 
the light and heat of the lamp or gas-flame used. The apparatus is re- 
ferred to in the “Botanische Practicum” as the Schuster Kugel—D. H 
CAMPBELL, Bonn. 
The influence of heredity upon vigor.—The results of two series of 
experiments with the tomato plant, carried on during the past three sea- 
sons, furnish a forcible illustration of the influence of the health of the 
parents upon progeny in plants. 
In the fall of 1883 a single plant was noticed in a row of tomatoes 
that appeared more feeble, and had more of its fruits decayed than any 
other. A few seeds were gathered from some of the sound fruits of 
this feeble plant, and at the same time, a few from sound fruits on a 
neighboring plant that appeared healthy and vigorous. The following 
spring the two samples of seeds were sown, and the young plants trans- 
planted to adjoining rows in the garden. It was a surprise to find that in 
habit the plants of each row closely resembled the parents, i. e., the prog- 
eny of the feeble plant was also feeble, even more so than was the parent, 
while that of the vigorous plant appeared entirely healthy. The differ- 
ence in the two rows was so marked that, but for the unquestionable 
identity of the fruit, one would scarcely have thought it possible that 
they could be of the same variety. The same selections of seed were con- 
tinued through 1885 and 1886, with like results. The past season the 
progeny of the feeble plant of 1883 scarcely exceeded one-fourth the size 
of that of the vigorous one. The plants lay prostrate on the ground, with 
discolored and shriveled foliage, and with the fruits fully one-half decayed 
before frost came. This decay isa soft rot, quite different from the black 
rot that so often affects tomatoes. The fruit becomes soft and collapses 
without changigg color, the skin finally bursts, permitting the contents to 
oflow out, cite, 2 skin dries without detaching itself from the plant. 
In the second series of experiments plants were grown through three 
successive generations from seed taken from quite immature fruits. In 
one instance seeds were gathered in every case from fruits that had not 
commenced to change color toward ripeness; in the other they were 
taken from entirely ripe fruits. It is of interest to observe that the effect 
of the immature seed upon the vigor of the progeny was precisely simi- 
lar to that of the seeds from the enfeebled plant above noted. The plants 
rew more and more feeble, until they failed to attain more than a fourth 
the size of those grown from ripe fruit. : ‘ 
Several varieties of tomatoes now cultivated show evidences in their 
manner of growth of having been originated by the selection of too imma- 
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