APPENDIX. 



107 



APPENDIX, 



A. The terms right and left are always used in anatomy, with reference to the right and left sides of the 

 subject's body. Similarly, by the anterior is always meant the head end, and by the posterior the hinder end. 

 The terms dorsal and ventral apply to the back and the belly respectively ; they are, however, often replaced 

 by terms bearing directly upon the position of the nervous axis, viz., neural and hasinal for the vertebrate, 

 haemal and neural for the invertebrate. 



B. The method of dissection from the side here employed has long been recognized as yielding results 

 second to no other, where a general survey of the animal's entire anatomy is recpaired. Moreover, by cutting 

 thus to one side of the middle line, the attachments of the organs are not interfered with, and they, therefore, 

 remain in position for detailed examination. 



In dissecting all the animals dealt with in this work, some such stand as that figured above will be found 

 useful; the rests for the arms may conveniently be lengthened to suit individual requirements, but the 

 swinging-arm, carrying a watchmaker's lens, will be found a necessity in examining delicate structures. 



All dissections should be performed under water, with the subject in a perfectly rigid position. For this 

 purpose a dish, such as is here figured, is necessary ; it should be preferably of glass, one-third filled with 

 paraffin blackened by the admixture of a little lamp-black. A slab of the above material admits of the 

 subjects being pinned down, and it should always be weighted at the bottom with lead, to avoid floating up. 



Should the water become clouded in dissecting, it must be at once changed, the cause of the obstruction 

 being, if possible, washed away. 



While dissecting, it is highly desirable that living specimens of the animal under consideration should be 

 kept constantly under observation, as many a structural feature is only intelligible on a knowledge of the 

 creature's habits. 



