398 THE POPULAR SCIENCE MONTHLY. 



A person who is deaf from birth is also absolutely dumb, until he 

 is trained to the use of speech ; he utters no cry. His lips and tongue 

 are motionless ; his mouth remains shut, his larynx is in a state of 

 unbroken repose ; he breathes only through the nostrils. When first 

 the effort is made to have him pronounce a letter written on the black- 

 board, it appears to be simply impossible for him to produce any 

 sound. The instructor shows the young mute how to open the mouth, 

 and how to hold the tongue and the lips. He places the child's hand 

 upon his own larynx, so that it may feel the movement necessary to 

 be performed. In the beginning, the simple expulsion of the breath 

 is difficult, but, after repeated exercise, there is a sort of stifled articu- 

 lation ; later, with some difficulty, a clear sound is obtained. In this 

 way the deaf-mute learns to pronounce all the vowels and consonants. 

 It needs but a short time to acquire the pronunciation of the labials. 

 Longer practice is needed in order to learn the play of the tongue, 

 and the proper mode of emitting the breath in articulating those eon- 

 sonants which call for only a slight intervention of the lips. Having 

 learned the alphabet, the mute begins to pronounce syllables and 

 phrases written on the blackboard. Finally, he speaks, and is under- 

 stood. He writes from dictation, with his eyes fixed upon the per- 

 son who addresses him questions, and makes his answers confidently. 



OUB COMMON MOULDS. 



By BYKON D. HALSTEAD 



THE following remarks are from personal observations which have 

 been made from time to time as circumstances would permit. 

 For convenience, the term mould will be extended beyond its narrow 

 technical meaning, and include all those forms of vegetable life which 

 are usually designated by that name. No lengthy argument is needed 

 to prove that mould is of common occurrence. It is a fact well known 

 to every person, from the wholesale provision-dealer down to the 

 hungry child who eats his crust upon the street. 



Where these plants do not grow it is difficult to say ; but to point 

 out the favorable conditions for their growth and some of the forms 

 which they there assume is an easier task, and to this part of the sub- 

 ject the reader's attention is invited. 



Moulds belong to that peculiar parasitic group of plants called 

 Fungi, the members of which never have anything like green leaves, 

 the workshops of higher plants, and are therefore unable to build up 

 their tissue from unorganized matter. They must feed upon that 

 which is already organized, either animal or vegetable, living or dead, 

 as the species will decide. 



