PLATE XXIII 
Malformed blossoms of tobacco (Nicotiana tabacum) caused by the mosaic disease, 
which is often responsible for the various abnormalities shown. The corolla may 
show mottling only, or it may develop very imperfectly, producing various degrees 
of catacorolla, fasciation, etc. In some instances the corolla fails to develop entirely. 
The plants producing these acquired abnormalities as a result of the mosaic disease 
have been studied as to their inheritance, but the descendants were healthy and their 
blossoms normal. A common cause of sterility is the failure of successful pollination 
of the stigma, owing to the abnormal displacement of pistil and stamens. Hand pol¬ 
lination of such blossoms has often given capsules containing an abundance of fertile 
seed. Blossoms as poorly developed as A, D, and H are usually incapable of producing 
seed. The anthers, however, sometimes contain functioning pollen which may pro¬ 
duce fertilization of the ovules when transferred to the pistils of healthy blossoms. 
Blossoms E, F, G, I, J, K, and L usually produce seed if hand pollination is practiced. 
(356) 
