144 DR. SCHULTZE. ON THE RHIZOPODA. 



served, is only the commencement of his labours in this de- 

 partment, is limited to the object of communicating faithful 

 observations with respect to the structure and vital phenomena 

 of the testaceous marine Rhizopoda, and to bring our know- 

 ledge of them, so far as possible, au niveau with the rapid 

 advances which have of late years 'been made in that of the 

 other Protozoa. 



One obstacle experienced by all who have addressed them- 

 selves to the study of the soft part of the Rhizopoda, and 

 which has probably altogether deterred many from it, has arisen 

 from the difficulty of procuring those creatures in the living or 

 well preserved state. Professor Schulfze mentions, as an en- 

 couragement to the study, that he found no difficulty in 

 bringing numbers of Polystomella strigilata, several GromicB, 

 RotalicB, and MiliolidrB, from Venice and Ancona to Griefs- 

 wald ; nor in keeping them alive for more than twelve months, 

 in as useful a condition for observation as on the first day. 

 He had, moreover, partially changed the sea-water but once 

 during the whole time. The water, however, contained living 

 UlvcB. He has also found that specimens from abroad, pre- 

 served in spirits of wine, served extremely well for the purpose 

 of studying the soft parts. 



Owing to the general similarity which exists apparently 

 throughout the rhizopodous class in the intimate structure of 

 the soft part, their systematic arrangement can only be founded 

 upon the shells, which exhibit an astonishing diversity of 

 form. Out of these forms it would appear, that the labours of 

 various naturalists in the last 100 years have made known 

 nearly 2,000 species of recent and fossil Foraminifera ; and 

 although the observations of Dr. Carpenter tend to show the 

 probability that very many of these supposed species are 

 merely varieties, still the number is sufficiently great to prove 

 the importance and interesting nature of the subject. Dr. 

 Schultze remarks upon the difficulties attending the study of 

 the Rhizopoda, and insists very properly upon the necessity 

 of viewing them in all positions, and under different modes of 

 illumination and of preparation, in order to arrive at a due 

 conception of their conformation. 



The work commences with a copious literature of the sub- 

 ject, and then, after a short historical introduction, pro- 

 ceeds to general considerations on the structure and vital 

 phenomena of the Rhizopoda, commencing with a description 

 of the hard part, or shell, followed by that of the soft tissue 

 contained therein. An account is then given of their nutrition, 

 reproduction (confessedly imperfect), and growth ; to which 

 succeed observations on the nature of the Polythalamia, as 



