188 



SCIENCE. 



NOTE ON THE SENSORY TRACT OF THE BRAIN. 



By Edward C. Spitzka, M. D., New York City. 



It is well known that Meynert (') and those who fol- 

 lowed that distinguished anatomist, believed that the 

 tract through which the conscious sensory impressions 

 reach the cortex, extends from the columns of Goll and 

 Burdach, of the cord and lower oblongata, through the 

 so-called superior or sensory decussation, to the anterior 

 pyramids ; that thence the tract runs with the anterior 

 pyramids in their outermost third through the pons and 

 pes pedunculi, courses between the thalamus and lenticu- 

 lar nucleus in the posterior third of the internal capsule, 

 and arching back, terminates in the cortex of the oc- 

 cipital lobe. Flechsig showed that what Meynert in- 

 terpreted as the sensory pyramidal decussation, has no 

 connection with the anterior pyramids, but, on the con- 

 trary, enters the lemniscus layer, or in'erolivary strand, 

 whose relations to the corpora quadrigemina had been 

 explained by Meynert, although he was befogged as to 

 its lower relations, owing to the aforesaid confounding 

 with the anterior pyramids proper. 



Now, Flechsig ('-) distinctly states in his work that the 

 explanation he has been able to furnish of the real nature 

 of the superior decussation, demonstrates the non-exist 

 ence of a direct tract from that decussation to the cortex. 



The true tract has, however, been kjiown to exist, al- 

 though the relations have not been properly interpreted. 

 The lemniscus layer is not only a detachment from the 

 corpora quadrigemina, but also distinctly incorporates a 

 peculiar bundle, described by Henle as a fasciculus, from 

 the pes to the tegmentum( 3 ). This tract continues, in 

 at least a part of the fibres, from the columns of Goll 

 and Burdach to the pes pedunculi and thence, no doubt, 

 to the cortex of the brain. The circuit for the conscious 

 sensory impressions transmitted by the cord, and pro- 

 posed by Meynert, therefore becomes re-established, 

 with a modification, namely, that the sensory tract does 

 not run through the pyramids and pons, but immediately 

 above them, and after entering the pes pedunculi prob- 

 ably takes the course claimed by Meynert. 



That there is a close relation between the pyramidal 

 tracts and the by-track from the superior decussation to 

 the pes pedunculi, is proven by an interesting observa- 

 tion which I have been able to make on the elephant's 

 brain. In this animal( 4 ) the entire pyramidal tract takes 

 the course of the by-track, that is, there are no vertical 

 fibres in the pons. The crus is continued bodily above the 

 latter (which is composed exclusively of transverse 

 fibres) to take the usual course on the ventral and me- 

 dial aspect of the olivary nucleus. 



This fact strengthens the proposition of Meynert, that 

 there intervenes a third projection series between that of 

 the tegmentum and that ot the pes pedunculi, for which 

 he proposes the name of the stratum intermedium ( 6 ). 

 In man, I believe this stratum intermedium to be the 

 main tract for the conveyance of conscious sensory im- 

 pressions from the general sensory periphery, while in 

 other animals, at least in the elephant, it is at the same 

 time the voluntary motor tract. 



That the sensory fibres occupy the most posterior por- 

 tion of the internal capsule, while they compose the 

 most dorsal in the pes pedunculi, shows that the fibres 

 of the latter must pursue a spirally twisted course 

 betore entering the brain. Such an arrangement seems 

 to be indicated, indeed, in the outer contours of the 

 crus. In an early human embryo, of about the third 

 month, I find a well marked columnar elevation running 

 from the outer part of the crus through the pons, where 

 it touches its fellow of the opposite side, and then passes 

 between the olives( 6 ). This I regard as the embryon- 

 ically distinct stratum intermedium. 



('). Das Gchirn dcr SaUselhicrc, in Strieker's Histology. 



('). Die Ltitunesbahnen d<s ( lehirnes und Riiekenm:irks. 1875. 



( 8 ). Lehrbuch der Anatomic des Menschen. 1872. 



(*). " Science," February 7, 1881. Archiv fuer Psychiatric 1874. 



(•). Demonstrated before the N. Y. Neurological Society, March i, 1881. 



ASTRONOMIAL MEMORANDA. 



A small pamphlet containing notes, corrections, etc., 

 to the " Handbook of Double Stars," has been recently 

 prepared by Messrs. Crossly, Gledhill and Wilson. In 

 the introduction, the editors say : " The corrections have 

 been thrown into two classes : the first contains those 

 which from their importance demand immediate atten- 

 tion in order to save waste of time. These the reader is 

 requested to insert at once. In the second list will be 

 found a large number of corrections which may be en- 

 tered as the stars are observed or read. 



A very copious set of additional notes has also been 

 drawn up, embodying, so far as we know them, the most 

 recent and improved orbits, measures and discoveries. 



It seems probable that the asteroid, No. 220, discovered 

 by Palisa on the 23d of March, is identical with No. 139, 

 Juewa. Juewa was discovered by the late Prof. Watson 

 while engaged upon one of the transit of Venus parties 

 in 1874 at Pekin. The asteroid was observed by Rum- 

 ker at Hamburg, on November 8th of the same year, but 

 since that date it has not been seen. 



Nature for March 17, contains the following note upon 

 the largest refractor in the world. "A very interesting 

 scientific work, the most important of its ki.id yet at- 

 tempted in the kingdom, has just been completed. It is 

 the great refracting telescope, constructed by Mr. 

 Grubb, of Rathmines, Dublin, for the Austro-Hungarian 

 Government, and it is to be placsd in the Observatory at 

 Vienna. A commission appointed by the Government 

 to examine the work, transmitted yesterday to the Austro- 

 Hungarian Embassy, in London, a report expressing 

 their full approval of the manner in which the task has 

 been completed. It is a matter of no little pride to Ire- 

 land that she has produced the largest refracting as well 

 as the largest reflecting telescope in the world." The 

 object glass of this instrument is 27 inches in diameter 

 or 1 inch larger than that of the Washington Refractor 

 made by Clark. 



W. C. W. 



Washington, D. C, April at, 1881. 



INTRA-MERCURIAL PLANETS. 



In " Science " of February 26, appeared an article on 

 the above subject by "W. C. W.," which I have read with 

 considerable personal interest, wherein we are led to in- 

 fer, from purely negative testimony alone, that no such 

 objects were seen during the total eclipse of Aug. 29, 

 1878, either by the late Prof. Watson or myself. Unfor- 

 tunately, Prof. Watson's tongue and pen are now silent, 

 and no one exists to defend his observations. What he 

 has written on the subject the astronomical world is 

 familiar with. It is about my own I wish to speak, and 

 in defending them against the negative testimony which 

 your correspondent brings, I hope to be able to convince 

 the reader that because the observers whom he cites saw 

 no planets, it is very far from proving their non-exis- 

 tence. 



If the reader will refer to the article itself, he will find 

 delineated on a chart the ground swept over by six ob- 

 servers, but he fails to tell us how short a time was de- 

 voted to a search west of the sun, and especially in the 

 immediate region of the two objects seen by me, and 

 near which one of Watson's objects was, viz., near 6 

 Cancri. As not one in a thousand of your readers will 

 have the priv ilege of reading the reports of those six 

 observers, just published by the Naval Observatory, and, 

 are therefore incapable of forming a correct conclusion 

 on the subject, 1 have thought it advisable to quote 

 what they really say, and, to remark, that when negative 

 testimony is arrayed against positive, it is very impor- 

 tant that its weight, if it has any, be carefully con- 

 sidered. 



