PROJECTION OF THE RETINA IN THE BRAIN 7 



These investigators, however, did not examine the pro- 

 jection of the retina in the primary optic stations themselves. 

 Recently Lubsen published a careful research on the tectum 

 opticum of a fish (Leuciscus rutilus) . In this animal Zeeman 

 made small lesions in the retina and Lubsen studied the 

 secondary degeneration in the primary optic neuron. 

 Stimulated by their work, I have made a study in rabbits 

 and in higher mammals. All the investigations in this sub- 

 ject have been made along with Dr. W. P. C. Zeeman, pro- 

 fessor of Ophthalmology at the University at Amsterdam. 

 We have examined about sixty brains of animals and studied 

 them with the help of the Marchi method microscopically in 

 a complete series. 



Prof. Zeeman made different kinds of lesions in the retina 

 of rabbits, cats and monkeys. To dilate the pupil atropine 

 was dropped into the animal's eye a day and again an 

 hour before the operation. Ether was used during the 

 operations on the monkeys and cats, in rabbits only cocaine 

 was administered in the eye. The eyehds were kept open 

 by retractors and by means of an electric lamp placed on the 

 forehead of the operator light was thrown on and into the 

 eye of the animal. With his right hand the surgeon inserted 

 a cataract needle with a sickle-shaped edge, through the 

 bulbar conjunctiva about 4 mm. behind the temporal 

 border of the cornea and then through the sclera into the 

 vitreous. With his left hand he now placed an ophthalmo- 

 scope lens of 20 dioptries before the eye. In this way he 

 could distinctly see the fundus and also the point of the 

 cataract needle in the vitreous. With his right hand he 

 brought this needle to the part of the fundus where the lesion 

 was to be made. In operations on the macula the blunt 

 side of the instrument was always turned towards the centre 

 of the macula, and after injuring the quadrant desired, the 

 incision was if necessary enlarged centrifugally. In a very 

 few cases the instrument had to be quickly extracted owing 



