MISSOURI BOTANICAL GARDEN BULLETIN 73 
of artists and engravers. The first volume, a copy of which is 
shown, is the only one published. Plants were described ac- 
cording to their qualities, either male or female, with a third 
class typified by a child symbolizing feeble effects. The follow- 
ing translation from the preface illustrates the style of the 
work. Discussing the planting of roots and herbs and the 
gathering of seed he says: ‘‘It is absolutely essential that 
these operations should be performed so as to correspond with 
the stations and positions of the planets and heavenly bodies, 
to whose control diseases are properly subject, and against dis- 
eases we have to employ herbs, with due regard, of course, to 
the sex, whichever it be, of human beings, and so herbs in- 
tended to benefit the male sex should be procured when the 
sun or moon is in some male sign, for example Sagittarius or 
Aquarius, but if this be impossible, at least when they are in 
Leo. Similarly herbs intended to benefit women should be 
gathered under some female sign, Virgo, or if that is impos- 
sible, under Taurus or Cancer.’’ 
SOME PROBLEMS AND EXHIBITS IN PLANT 
PATHOLOGY 
Important Diseases of Plants Induced by Filterable Viruses. 
—Variegation and chlorosis in plants are common phenomena. 
Some variegated foliage (using variegation in this account to 
indicate green leaves which are blotched, mottled, striped, or 
edged with white or yellow) are characteristic of established 
or “natural’’ ornamental varieties of cultivated plants. Other 
types of variegation are infectious from a very slight to a 
very high degree. 
Of the infectious types of variegation or mottling the 
‘(mosaic’’ diseases are among the most disastrous, these being 
diseases even in the popular sense,—causing injury and often 
ereat loss to cultivated crops. The mosaic disease of tobacco, 
often known as ‘‘ealico,’’ is one of the most common of these 
maladies and is a disease widely distributed throughout the 
world. It is highly infectious, through the stings and bites 
of insects, and is readily transferred by mechanical or other 
artificial means. It has been definitely shown that this dis- 
ease is caused by a ‘‘filterable virus,’’ that is, a disease, the 
infective particles of which will pass the pores of the usual 
porcelain bacteriological filters. 
