134 THE AMERICAN MONTHLY [July, 
these little fellows require a great deal of ventilation—he can watch and regis- 
ter their daily changes as they grow toward their adult form. Thus the bar- 
nacle, common as it is, will furnish abundant material for a summer study. 
The eggs may be obtained and their segmentation watched ; the young nau- 
plius may be studied, and the grafting upon it later of the more complex 
cypris stage, the final changes in this, and the attachment of the hitherto free 
creature, and the assumption of a sedentary habit. Or he may obtain egg- 
cases of some of the numerous snails and watch the growth of a snail from 
the egg through its larval veliger stage; or catch in his net the free-swim- 
ming embryos of various worms and watch them grow a tail by budding ; or 
readily fertilize for himself the eggs of echinoderms, and see every change from 
the unfertilized ovum through the very interesting larva form to the adult 
shape. 
All these and many other lines of study are open to the interested student 
who lives near the sea-shore ; and there are many books which will help him 
to pursue them to advantage. Many of them require no expensive outfit, 
and they open the way to the most interesting and attractive paths of study 
of the whole field of zoology, as well as to many interesting lines of work 
in botany. 
But the student who lives inland, beyond reach of the shore, is not, by 
any means, shut out from such lines of research; though, in his case, fewer 
are accessible. Whole groups of animals are, indeed, exclusively marine. 
Thus the echinoderms, and some life-histories of widest interest, are to be 
studied only in marine forms. But there is, for all that, enough among 
fresh-water forms to occupy any one many years, and to interest and instruct 
all. Thus the little gelatinous masses so common on submerged twigs 
of any quiet pond are bunches of the eggs of snails. These are easily 
obtainable in all stages of development. They are, by reason of their great 
transparency, very favorable for study. They also furnish the student an 
opportunity to reach, perhaps, valuable original results; for the authorities 
are disagreed upon the main facts in the development of the pond snails. 
Very interesting objects of study are too numerous to mention :—The poly- 
zoa and their habits; /Zydra in the living state; living plants, such as con- 
jugating filamentous alge, moving diatoms, etc. Some of these may be 
kept indefinitely in aquaria and used for winter study; others may be pre- 
served and studied by section or otherwise. _ One who in the summer stops 
his studies makes a great mistake ; it should be his time of greatest activity. 
o—_—— 
Microscopical demonstrations.—Mr. Arthur J. Doherty, of 19 Bl-s- 
som avenue, Manchester, Eng., desires us to state that he will be at liberty 
to give the under-mentioned series of demonstrations in practical microscop- 
ical work before societies in this country :— 
Animal and plant section cutting. 
Single and double staining. 
Anatomical injecting. 
Selecting and arranging foraminifera. 
Mounting in balsam and other media with and without pressure. 
The mechanical and optical construction of the lantern microscope, includ- 
ing an exhibit of a number of beautiful objects by means of the instrument. 
Mr. Doherty leaves England for Australia upon the 23d July, and any 
communication to him should be addressed to the general post-office, Sydney, 
New South Wales. If he can make a sufficient number of engagements to 
pay expenses he will make the trip to the United States across the Pacific. 
We are glad to commend this project to our readers as one which will be 
