322 0. P. HOWAED 



just posterior to the equator of the ball. Bearing in mind the attachments 

 of the plain muscle described by Landstroem, we must admit that the 

 eye signs become readily explainable: thus a spastic condition of the 

 muscle would have as its first effect a widening of the lid slit or Dalrym- 

 ple's sign: the free movement of the eyelids being thus interfered with, 

 an incoordination of the movements of the eyeball and lids would result 

 (von Graefe's sign). The superior and inferior tarsal muscles running 

 vertically in the lids doubtless plays a considerable part in the production 

 of both Dalrymple's and von Graefe's sign. 



Protrusio bulbi is produced when the hypertonicity of the plain muscle 

 overcomes the tonus of its antagonistic recti muscles. Convergence of 

 the eye increases the distance between the origin and insertion of the 

 mesial portion of the cone of plain muscle, which is, as a result, well 

 developed to meet this oft-repeated act, A spastic condition of the plain 

 muscle would tend to overcome the tonus of its antagonist the internal 

 rectu's and a break in convergence would result (Moebius' sign). 



Landstrocm's findings and conclusions were subsequently challenged 

 by a fellow countryman, Troell (a), who, in his first paper in 1914, raised 

 the following objections: First, that the Landstroem muscle is so weak 

 and so asymmetrically placed as to be hardly capable of producing the 

 eye signs alone. Secondly, it is above all difficult to understand how 

 a contraction of that muscle should produce a pronounced shifting forward 

 of the posterior origin and thus of the entire eyeball and not a shif ting- 

 back of its anterior origin, since the former is a point considerably more 

 fixed than the latter. Thirdly, even granting the possibility of the above 

 forward movement and assuming that the contracted condition of the 

 muscle is the result of a stimulation of the sympathetic fibers, how can 

 one account for the ocular signs being unilateral in 10 per cent of cases 

 and pupillary signs not being part of the syndrome and only occurring 

 twice in his series of 164 cases? Troell (fr), however, believes it wise to 

 offer no theory as a substitute for Landstroem's, but proceeds to ex- 

 perimental investigation, the results of which he published in 1916. He 

 succeeded in producing exoplithalmos and the lid phenomena in dogs 

 by the subcutaneous injection of paraphenylenediamin hydrochlorid and 

 that even after one sympathetic ganglion had been removed. Troell finally 

 admits that the problem of the production of the ocular signs of exoph- 

 thalmic goiter remains unsolved. 



Finally one must consider what produces an increased tone in the 

 various muscle bands of Mueller and Landstroem. It is generally as- 

 signed to a sympatheticotonic response. Long ago Fr. Mueller con- 

 sidered the probability of some action of the thyroid gland upon the 

 sympathetic ganglion in the neck, as suggested by two cases of unilateral 

 exophthalmos in which there was goiter on the same side; in one of the 

 two, the goiter, and at that time also the exophthalmos, had been bi- 



