STATE HORTICULTURAL SOCIETY. 35 



CRYPTOGAMOUS DISEASES. 



There are several kinds of blight, common to the pear, three of which we propose to 

 describe. 1st. Blight of leaves. This form is caused by a broad or ttat-headed fungus ; it 

 spreads rapidly, attaching itself to the leaves which are soon killed. This fungi is so large 

 that It may be seen by the naked eye. Seedling pear trees are most injured by it. The 

 leaves of the budded pear tree suffer most when standing near seedlings. We know of 

 no remedy for this form of blight. 2nd. Pear tree blight, or fire-blight, so-called. 

 This blight is induced by an extremely minute fungus, seen only by the aid of a power- 

 ful microscope. The spores enter the pores of the bark, and when the conditions are 

 favorable they quickly vegetate. This fungi may be collected with a damp camels hair 

 brush, and when macerated in water and placed in contact with the alburnum as in 

 budding, especially when the circulation is most active, readily mixes with the sap, 

 altering the form of the particles much the same as poison from the bite of insects or 

 reptiles, is known to act on the blood of animals. The infusion of the seculent portions 

 of fundus into the sap of the pear produces a change in the form of the particles of 

 the sap ; and by reason of this altered form it is no longer normal sap, and can in no 

 way aid in the formation of, or give the true form of granulated or woody matter ; it 

 has, therefore, become a foreign substance, and can not contribute to the growth of 

 the plant. In this condition both the sap and the granulated matter produced is so 

 different in form from trees in health that the circulation is measurably arrested, and 

 fermentation in the affected part takes place. 



In some instances, as when plants are in most active growth, it dams up the 

 downward circulation ; this in connection with fermentation takes place to such an 

 extent as to cause ruptures in the bark, when in some instances the diseased sap will 

 run down many feet on the outside of the branch or trunk of the tree. Trees attacked 

 by this pear fungi late in the season, also trees that early mature their growth, escape 

 with the loss of the outer portions of the bark ; in these cases the fermented sap dries 

 up, producing those dead patches of bark so commonly seen ; but when the disease 

 appears early in the season on all trees of late growth, it generally penetrates through 

 the bark to the alburnum, where it is quickly disseminated to other parts of the tree. 

 Gray, in his Elements of Botany, says vegetable cells of our trees are so minute that 

 from 27 to 125 millions may be contained in the compass of a cubic inch. Taking the 

 smallest of these and knowing the measurement of certain cryptogamic vegetation as 

 given by Prof. Barnard, we find the asstonishing number of (8,000) eight thousand of 

 these vegetable forms may be contained in a cell. Now, if we are at all pushed to 

 know why these cryptogamous diseases of plants spread so rapidly, it is only necessary 

 to consider the facility with which this infusoria is sub-divided. 



Prof. Shrenberg, "from his observations upon the multiplication by sub-division of 

 a few individuals of a single species of Paramecium computed that in a month 108,000,- 

 000 might proceed from a single one." What is true of animals, is true of vegetable 

 life. 



Hear what Prof. Barnard says : " But another discovery has been brought to light by 

 the microscope among those humble forms of life. The unicellular are generally at least 

 at one period of their existence free and not like the larger vegetables anchored by 

 stems for life to some particular spot, and with their freedom they possess a power of 

 locomotion which likens them more fully to the animals they so much resemble. * * 



