86 



THE AMERICAN MONTHLY 



[May, 



placing a few water-snails in a jar of 

 water. In a short time the clear, 

 transparent, jelly-like spawn will be 

 found attached to the sides of the 

 vessel, from which it may be de- 

 tached without injury. The sim- 

 plest way to observe the changes 

 which lead to the development of 

 the snails is to take a two-ounce, 

 wide-mouthed bottle and almost fill 

 it with clean water. In this bottle 

 the spawn may be allowed to remain 

 exposed to the light, but not to 

 direct sunlight, except for a short 

 time during each day. Under such 

 conditions the development will go 

 on rapidly, and the process can be 

 observed under the microscope 

 from time to time, by placing the 

 specimen in a deep cell — a Holman 

 slide is good for the purpose. 



We have only mentioned a very 

 few of the interesting objects that 

 are to be found by any person, 

 during an afternoon ramble in the 

 country where ponds or streams 

 abound. If tliese short articles 

 would serve to arouse a real interest 

 in collecting, if they would induce 

 amateur microscopists to go out and 

 look for themselves, to take notes 

 of what they find, and make care- 

 ful drawings of the objects they 

 find, we would be very glad to 

 know it. 



We are often met with the remark 

 from amateur collectors that they 

 cannot name the forms they meet 

 with. 



While it is true that it is a real 

 satisfaction to name an object, or at 

 least to know to what genus of ani- 

 mals or plants it belongs, most 

 collectors must be contented with a 

 very superficial knowledge of the 

 forms of microscopic liie. Only 

 those who are willing to devote one 

 or more years to hard study during 

 spare hours can hope to name ob- 

 jects ; elementary books are of com- 

 paratively little value for this pur- 



pose. Such books are pleasing to 

 read, and profitable so far as they 

 give the student a general idea of 

 the nature of the objects to be 

 found ; but when they are the sole 

 reliance of the observer for naming 

 his objects, they are more likely to 

 confuse him than to do him good 

 service. By all means, then, we 

 advise every one who desires to 

 name specimens to confine his 

 studies mainly to a certain depart- 

 ment of study, to obtain the best 

 works on the subject, and to discard 

 the elementary ones. One authori- 

 tative work, even though its cost is 

 considerable, is worth much more, 

 even to the amateur, than a dozen 

 of the little books designed to pop- 

 ularize science. 



Therefore, if a person desires to 

 study the Infusoria, we would ad- 

 vise him to buy a copy of Prit- 

 chard's " Infusoria," even though a, 

 second-hand copy should cost him 

 $25 ; if he chose the Algse of fresh 

 water, the best work is Rabenhorst's 

 "Flora Alganim," which costs 

 about $9, and so in every depart- 

 ment of study, we advise the 

 student to get the best books, 

 and they will be always valuable. 

 For an elementary work of real 

 utility, we know of nothing that i& 

 so good and so reliable as the work 

 of Eyferth, which is being pub- 

 lished in this JoDEXAL. If used 

 carefully, a little experience will 

 enable any person to determine the 

 genus of almost anything he meets- 

 with, and this artificial key to class- 

 ification will be valuable, even to 

 those who have larger works. 

 Several subscribers have said to us 

 that Eyferth's key does not enable 

 them to name their objects. This 

 is partly because they have not 

 made themselves familiar with tlie 

 meaning of a few technical words, 

 but more particularly because it is 

 absolutely impossible to make any 



