December 28, 1883.) 



SCIENCE. 



6.33 



theliuiii as a sheet of protoplasm with scattered nuclei 

 has been committed over and over again by persons 

 not trained in histology.) The description of the 

 course of the nerves rectifies previous accounts. — 

 (Ann. sc. nat. zobl., siv. art. 2.) c. s. M. [573 



Crustaceans. 

 Isopoda of the Blake dredgings. — In a report 

 on the Isopoda dredged on the east coast of the United 

 States in ISSO, by the U. S. coast-survey steamer 

 Blake, under the direction of Alexander Agassiz, 

 Oscar Harger says that the collection, although small, 

 is remarkable for the large proportion of interesting 

 forms; since nearly ,ill the species are either new, or 

 not hitherto known upon our coast, or known only 

 from single specimens. Nine species, all belonging 

 to Cirolanidae and Aegidae, are enumerated, and 

 most of them fully described and figured on four 

 excellent photo-lithographic plates from the author's 

 drawings. — (Bull. mu.i. comp. zooJ., xi., no. 4, Sept., 

 1883.) s. I. s. [574 



Development of Panopeus. — E. A. Birge do- 

 scribes and figures the post-embryonal and some of the 

 later embryonal stages of Panopeus Sayi and the sec- 

 ond zoea stage of P. depressus. He describes four 

 distinct zoea stages after the casting of the embryonic 

 cuticle (or ' larval skin,' as Prof. Birge calls it) and a 

 ' first megalops stage," and discusses the metamor- 

 phoses undergone by the body and appendages in the 

 change from each stage to the ne.xt. After describ- 

 ing the 'first megalops stage,' Prof. Birge says, 

 "Subsequent changes in the megalops afiect the pro- 

 portions of the carapax, which becomes broader pro- 

 portionally, and that of the abdomen, which becomes 

 .smaller, and is permanently flexed under the sternum. 

 The appendages undergo many changes, gradually 

 approximating them to the adult form. The last 

 stage is reached after several — at least four — moult- 

 ings." Unfortunately none of these remarkable later 

 megalops stages are described or figured, as they cer- 

 tainly deserve to be if actually observed. During 

 several seasons' observations the writer has found no 

 evidence of more than one megalops stage in this 

 or allied species; and, with the exception of Bate's 

 doubtful observations on Careinus, there are appar- 

 ently no well authenticated cases of several megalops 

 stages in any species of Brachyura. The numerous 

 figures illustrating the paper are rude and inaccurate. 

 — {Stud. biol. lab. Johns Hojtk. unh-., ii., no. 4, July, 

 ISS;?.) s. I. 8. |575 



Insects. 

 Sucking-apparatus in butterflies. — P. Kirbach 

 describes the structure of the maxillae and pharyn.x 

 in the Lepidoptera precisely as described by Burgess 

 in the American naturalist for May, 1S80, and more 

 at length in a memoir on the anatomy of the milk- 

 weed butterfly in the Anniv. memoirs Host. soc. nat. 

 hist., 1881. Kirbach makes no reference to either of 

 these papers, though both were recorded in the very 

 journal containing his article, as well as in Carus's 

 Zool. jabresberichthy Bertkau, in the Arrh.f. nalur- 

 gesch., and in the Zuoloijical record. However, it is 

 satisfactory to have observations independently con- 



firmed; and Kirbach gives almost a verbal and pic- 

 torial repetition of the above-quoted papers. Thus 

 the suspensory muscles of the phatynx receive the 

 identical names given them by Burgess. Kirbach 

 believes the proboscis is extended by muscular con- 

 traction, and rolled up by elasticity, but gives no proof 

 of his view. This is the opposite of what the mus- 

 cular arrangement .teemed to Burgess to indicate; 

 although he added that " it is more probable we fail 

 to see, or to correctly interpret, some proper muscular 

 mechanism for both movements of the proboscis." 

 Unfortunately, Kirbach does not help us here. 



Kirbach describes, for the first time, the syringe- 

 like mechanism of the salivary diict, by which saliva 

 is injected into the proboscis. This arrangement was 

 overlooked by Burgess. — (Zool. anz., vi. 553.) E. B. 



1 576 



■Wheat-stem maggot or bulb--worm. — The larva 

 of Meromyza americana Fitch has been very de- 

 structive this year to wheat and rye in Fulton county, 

 111. Important additions to the published observa- 

 tions of Fitch, Riley, and Lintner, have been made 

 by S. A. Forbes, who gives descriptions and figures 

 of all stages of this insect. The egg is now figured 

 for the first time, and a winter brood has been ob- 

 served. — ( Prairie farmer, Aug. 4.) j. h. c. [577 



VERTEBRATES. 



Histology of the nervous centres. — C. Golgi 

 has investigated the morphology of ganglion-cells. 

 His conclusions are in some respects very different 

 from those of previous investigators, and, if confirmed, 

 will mark an important advance in our knowledge 

 of the subject. On this account we give a longer 

 abstract than usual for special papers. 



The origin of the nervous fibres depends on certain 

 constant laws, uniform for the different centres, de- 

 spite certain secondary differences in the morphology 

 and distribution of the histological elements. The 

 ganglion-cells may in general be distinguished from 

 the other cells by their form, the appearance of their 

 nuclei, and the mode of origin of their prolongations; 

 but they are especially characterized by the presence 

 of the simile nervous (Deiter's) process, which olone 

 enters into connection with the nerve-fibres to make 

 part of, or constitute them. The protoplasmatic 

 processes have nothing to do with the origin of the 

 nerve-fibres, directly or indirectly: they are in rela- 

 tion with the connective-tissue corpuscles (exactly 

 how is not shown, so this may be questioned). As 

 each cell has only one Deiter's process, it follows 

 that they are all really unipolar. The sensory and 

 motor cells cannot be distinguished definitely by their 

 form or size from one another: but, as regards Dei- 

 ter's process, two forms are distinguished, — the first 

 is supposed to go with the motor cells, the second with 

 the sensory. The established view that the process 

 is continued without branching into the axis-cylin- 

 der is discarded; for Golgi maintains that it gives off 

 a more or less considerable number of filaments on 

 its way. In the first form, the process, although giv- 

 ing oS filaments, still maintains its Individuality, 

 and can be followed to the points where it enters the 



