1889.] MlCllOSCOPICAL JOUKNAL. 1S3 



Methods of Mounting Infusoria. 



By Prof. C. W. HARGITT, 



OXFORD, OHIO. 



Of the many accomplishments of microscopy, its subjects and meth- 

 ods, not the least of its value consists in the fact that a very large portion 

 of the work may, by mountings and photography, be rendered as per- 

 manent as the cabinet of the mineralogist. An exception is sometimes 

 urged, however, concerning that large class of the utmost interest to 

 the microscopist, viz., the Infusoria. This is especially true of the more 

 delicate and perishable forms, such as the paramcccia, vorticellai, etc., 

 some of which are rare and difficult to obtain. Specially is this true 

 of the critical moment when they are most needed, as every teacher of 

 zoology can testify. While the peculiar beauty and interest which at 

 taches to the observation of the living- forms may be wanting in them 

 in the motionless state of the mounted specimen, yet a world of inter- 

 est is exhibited in the silent form which cannot be aroused by any figure 

 however well executed, and that simply in the fact that it is the thing 

 itself. But, further, the motionless form on the slide is often far more 

 instructive than the same form living. If properly killed, so that it re- 

 tains the natural features, and properly stained, far more of its structure 

 may be seen than is possible in life. 



There can be no doubt, therefore, that a successful method bv which 

 these results may be had will be welcomed by not only the teacher, to 

 whom it is a very boon, but also by the curiosity hunter of microscop- 

 ical gems. That it is no easy problem goes without saying. The very 

 delicacy of many forms, and their extreme sensitiveness to stimuli of 

 unfavorable sorts, renders their killing and preparation in any success- 

 ful way very difficult. I have recently had some success in this line 

 that has been a surprise to many besides myself, and a brief detail of 

 the method may help others to similar results. I am aware that other 

 methods have been proposed by other workers from time to time, and 

 I do not presume that I am the first or only one by any means who has 

 been able to secure reasonably good results in this line of work. That 

 the method used by me is, however, a success when carefully followed, 

 I can fully affirm. Neither am I disposed to claim originality for the 

 method, except in some of the details of its application. It was first 

 suggested to me by Dr. E. B. Wilson, though since modified to suit 

 special cases. 



The first requisite is to '• catch the hare." Assuming that the mate- 

 rial to be experimented upon is possessed in abundance, whether of 

 paramopcia or vorticella?, or hydroids, or even Amadiie, it is only 

 necessary to expose in a shallow dish or watch-glass some of the water, 

 as free as possible from sediment or debris, preparatory to killing, which 

 is a matter of the greatest importance. Before attempting this it is 

 well to get rid of as much of the water as possible without endangering 

 the normal activity of the animals. It is by some suggested to be done 

 by leaving to slow evaporation. I have found this rather risky, as many 

 are likely to perish. My method has been to draw oH' the surface very 

 gently with small pipette, and then further reduce the excess of water 

 by a syphon of thread which draws it ofl' by capillarity. Next comes 

 the process of killing, which must be done absolutely instantaneously, 

 and at the same time without injury to the most delicate organism. The 



